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A101553
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A modular recurrence.
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1
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1, 5, 15, 75, 225, 1125, 3375, 16875, 50625, 253125, 759375, 3796875, 11390625, 56953125, 170859375, 854296875, 2562890625, 12814453125, 38443359375, 192216796875, 576650390625, 2883251953125, 8649755859375, 43248779296875
(list; graph; refs; listen; history; internal format)
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OFFSET
| 0,2
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COMMENTS
| Interpolated zeros suppressed.
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FORMULA
| a(0)=1, a(1)=0, a(n)=(3+2*mod(n/2, 2))a(n-2). a(n)=A100747(2(n+1))/3.
a(2n) = 15^n, a(2n+1) = 5*15^n. - Ralf Stephan, May 16 2007
O.g.f.: (1+5x)/(1-15x^2). - DELEHAM Philippe, Dec 02 2011
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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: A149651 A149652 A151487 * A149653 A149654 A149655
Adjacent sequences: A101550 A101551 A101552 * A101554 A101555 A101556
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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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