Search: a079878 -id:a079878
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1, 2, 8, 32, 46, 392, 12230, 155942, 659488, 1025582, 1047128, 3437088, 1449322158, 1452777560, 1691887144, 4558298126, 4840156480, 39554086678, 353617531486, 608231808384, 619986226720, 969355365422
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OFFSET
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1,2
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COMMENTS
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LINKS
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FORMULA
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EXAMPLE
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A079878(46)=46, which adds 46 to the sequence.
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PROG
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(Haskell)
import Data.List (elemIndices)
a200063 n = a200063_list !! (n-1)
a200063_list = map (+ 1) $ elemIndices 0 $ zipWith (-) [1..] a079878_list
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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1, 2, 53, 5, 71, 26, 9, 8, 19, 72, 149, 27, 91, 18, 21, 17, 43, 20, 29, 50, 35, 150, 45, 28, 99, 92, 773, 34, 171, 42, 33, 32, 123, 44, 49, 41, 75227, 58, 137, 51, 295, 48, 789, 68, 47, 46, 65, 57, 891, 100, 269, 90, 111, 428, 921, 64, 131, 172, 105, 203
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OFFSET
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1,2
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COMMENTS
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LINKS
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PROG
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(Haskell)
import Data.List (elemIndex)
import Data.Maybe (fromJust)
a200087 n = (fromJust $ elemIndex n a079878_list) + 1
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KEYWORD
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nonn
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AUTHOR
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STATUS
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approved
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A064434
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a(n) = (2*a(n-1) + 1) mod n.
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+10
6
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0, 1, 0, 1, 3, 1, 3, 7, 6, 3, 7, 3, 7, 1, 3, 7, 15, 13, 8, 17, 14, 7, 15, 7, 15, 5, 11, 23, 18, 7, 15, 31, 30, 27, 20, 5, 11, 23, 8, 17, 35, 29, 16, 33, 22, 45, 44, 41, 34, 19, 39, 27, 2, 5, 11, 23, 47, 37, 16, 33, 6, 13, 27, 55, 46, 27, 55, 43, 18, 37, 4, 9, 19, 39, 4, 9, 19, 39, 0
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OFFSET
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1,5
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COMMENTS
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a(n) is the remainder when (2*a(n-1) + 1) is divided by n.
Can be generalized to a(n) = f(a(n-1)) mod n, where f is any polynomial function.
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LINKS
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FORMULA
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a(n) = (a(n-1) * 2 + 1) mod n.
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EXAMPLE
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0, (0*2+1) mod 2 = 1, (1*2+1) mod 3 = 0, (0*2+1) mod 4 = 1, (1*2+1) mod 5 = 3 (3*2+1) mod 6 = 1.
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MATHEMATICA
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nxt[{n_, a_}]:={n+1, Mod[2a+1, n+1]}; Transpose[NestList[nxt, {1, 0}, 80]][[2]] (* Harvey P. Dale, Feb 10 2014 *)
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PROG
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(PARI) { a=0; for (n=1, 1000, a=(2*a + 1)%n; write("b064434.txt", n, " ", a); ) } \\ Harry J. Smith, Sep 13 2009
(Magma) [n le 1 select n-1 else (2*Self(n-1)+1) mod n: n in [1..80]]; // Vincenzo Librandi, Jun 24 2018
(GAP) a:=[0];; for n in [2..90] do a[n]:=(2*a[n-1]+1) mod n; od; a; # Muniru A Asiru, Jun 24 2018
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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Jonathan Ayres (JonathanAyres(AT)btinternet.com), Oct 01 2001
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STATUS
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approved
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1, 3, 79, 235, 431, 1503, 2943, 6059, 6619, 18911, 54223, 302467995, 1772665631, 2148845167, 5145362667, 129465909327, 212089391807
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graph;
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listen;
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internal format)
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OFFSET
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1,2
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COMMENTS
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LINKS
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PROG
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(ARIBAS): a := 0; for n := 1 to 3000000000 do am := a; a := (am*2 + 1) mod n; if a = 0 then write(n, " "); end; end;
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CROSSREFS
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KEYWORD
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nonn,more
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AUTHOR
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Jonathan Ayres (JonathanAyres(AT)btinternet.com), Oct 01 2001
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EXTENSIONS
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STATUS
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approved
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