Revision History for A332170
(Underlined text is an addition;
strikethrough text is a deletion.)
Showing all changes.
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#9 by M. F. Hasler at Tue Feb 11 08:24:27 EST 2020
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#8 by M. F. Hasler at Tue Feb 11 08:23:52 EST 2020
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| MATHEMATICA
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Array[7 ((10^(2 # + 1)-1)/9 - 10^#) &, 15, 0]
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| STATUS
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approved
editing
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#7 by M. F. Hasler at Sun Feb 09 09:56:59 EST 2020
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#6 by M. F. Hasler at Sun Feb 09 09:38:15 EST 2020
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| MAPLE
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A332170 := n -> 7*(10^(2n2*n+1)-1)/9-7*10^n;
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approved
editing
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#5 by M. F. Hasler at Sun Feb 09 01:03:48 EST 2020
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#4 by M. F. Hasler at Sun Feb 09 01:03:45 EST 2020
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| MATHEMATICA
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Array[7 ( ((10^(2 # + 1)-1)/9 - 7*10^# &, ^#) &, 15]
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| PROG
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(PARI) apply( {A332170(n)=)=(10^(n*2+1)\9*7-7*10^n)*7}, [0..15])
(Python) def A332170(n): return (10**(n*2+1)//9*7-7*10^n)*7
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| CROSSREFS
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Cf. A138148 (cyclops numbers with binary digits only), A002113 (palindromes).
Cf. A332120 .. A332190 (variants with different repeated digit 2, ..., 9).
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approved
editing
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#3 by M. F. Hasler at Sat Feb 08 22:03:01 EST 2020
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#2 by M. F. Hasler at Sat Feb 08 21:59:49 EST 2020
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| NAME
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allocated for M. F. Hasler
a(n) = 7*(10^(2n+1)-1)/9 - 7*10^n.
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| DATA
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0, 707, 77077, 7770777, 777707777, 77777077777, 7777770777777, 777777707777777, 77777777077777777, 7777777770777777777, 777777777707777777777, 77777777777077777777777, 7777777777770777777777777, 777777777777707777777777777, 77777777777777077777777777777, 7777777777777770777777777777777
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| OFFSET
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0,2
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| LINKS
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<a href="/index/Rec#order_03">Index entries for linear recurrences with constant coefficients</a>, signature (111,-1110,1000).
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| FORMULA
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a(n) = 7*A138148(n) = A002281(2n+1) - 7*A011557(n).
G.f.: 7*x*(101 - 200*x)/((1 - x)(1 - 10*x)(1 - 100*x)).
a(n) = 111*a(n-1) - 1110*a(n-2) + 1000*a(n-3) for n > 2.
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| MAPLE
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A332170 := n -> 7*(10^(2n+1)-1)/9-7*10^n;
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| MATHEMATICA
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Array[7 (10^(2 # + 1)-1)/9 - 7*10^# &, 15]
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| PROG
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(PARI) apply( {A332170(n)=10^(n*2+1)\9*7-7*10^n}, [0..15])
(Python) def A332170(n): return 10**(n*2+1)//9*7-7*10^n
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| CROSSREFS
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Cf. A002275 (repunits R_n = (10^n-1)/9), A002281 (7*R_n), A011557 (10^n).
Cf. A138148 (cyclops numbers with binary digits only).
Cf. A332171 .. A332179 (variants with different middle digit 1, ..., 9).
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| KEYWORD
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allocated
nonn,base,easy
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| AUTHOR
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M. F. Hasler, Feb 08 2020
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| STATUS
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approved
editing
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#1 by M. F. Hasler at Thu Feb 06 20:55:20 EST 2020
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| NAME
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allocated for M. F. Hasler
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| KEYWORD
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allocated
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| STATUS
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approved
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