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A100747
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A modular recurrence.
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1
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1, 3, 15, 45, 225, 675, 3375, 10125, 50625, 151875, 759375, 2278125, 11390625, 34171875, 170859375, 512578125, 2562890625, 7688671875, 38443359375, 115330078125, 576650390625, 1729951171875, 8649755859375, 25949267578125
(list; graph; refs; listen; history; internal format)
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OFFSET
| 0,2
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COMMENTS
| Interpolated zeros suppressed. The inverse mod 2 binomial transform of 2^n is 1,1,3,3,15,15,... (A100735).
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FORMULA
| a(0)=1, a(1)=0, a(n)=(5-2*mod(n/2, 2))a(n-2). a(n)=A101553(2(n+1))/5.
a(2n) = 15^n, a(2n+1) = 3 * 15^n. - Ralf Stephan, May 16 2007
O.g.f.: -(1+3*x)/(-1+15*x^2) . - R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Feb 04 2008
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MAPLE
| a:=n->mul(4+(-1)^j, j=1..n):seq(a(n), n=0..23); # [From Zerinvary Lajos (zerinvarylajos(AT)yahoo.com), Dec 13 2008]
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CROSSREFS
| Sequence in context: A074355 A201868 A005560 * A100737 A178669 A110464
Adjacent sequences: A100744 A100745 A100746 * A100748 A100749 A100750
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KEYWORD
| easy,nonn
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AUTHOR
| Paul Barry (pbarry(AT)wit.ie), Dec 06 2004
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