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A271341
Somos's sequence {a(4,n)} defined in comment in A018896.
7
1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 2, 3, 4, 5, 6, 10, 19, 35, 60, 156, 284, 499, 930, 1836, 7116, 21586, 52869, 115344, 356076, 972840, 3350009, 11844969, 37689894, 215136930, 785604755, 2444023816, 7985904285, 36968693334, 230985863335, 1429813280831, 6838592493455, 27144055289355, 191201731942399
OFFSET
0,11
COMMENTS
The sequence of the first differences begins from 9 zeros, 5 1's and 4 consecutive squares, beginning with 2^2.
A generalization see in the comment in A018896.
LINKS
MATHEMATICA
k = 4; Set[#, 1] & /@ Map[a[k, #] &, Range[0, 2 k + 1]]; a[k_, n_] /;
n >= 2 k + 2 := (a[k, n - 1] a[k, n - 2 k - 1] + a[k, n - k - 1]^2) / a[k, n - 2 k - 2]; Table[a[k, n], {n, 0, 42}] (* Michael De Vlieger, Apr 04 2016 *)
a[n_ /; 0 <= n <= 10] = 1; a[n_]:= a[n] = (a[n-1]*a[n-9] + a[n-5]^2)/a[n -10]; Table[a[n], {n, 0, 40}] (* G. C. Greubel, Feb 21 2018 *)
PROG
(PARI) {a(n) = if(n< 10, 1, (a(n-1)*a(n-9) + a(n-5)^2)/a(n-10))};
for(n=0, 40, print1(a(n), ", ")) \\ G. C. Greubel, Feb 21 2018
(Magma) [n le 10 select 1 else (Self(n-1)*Self(n-9) + Self(n-5)^2 )/Self(n-10): n in [1..40]]; // G. C. Greubel, Feb 21 2018
KEYWORD
nonn
AUTHOR
EXTENSIONS
More terms from Michael De Vlieger, Apr 04 2016
STATUS
approved