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A154633 a(n) = (4*n+1)*(4*n+3)*(4*n+5)*(4*n+7). 2
105, 3465, 19305, 62985, 156009, 326025, 606825, 1038345, 1666665, 2544009, 3728745, 5285385, 7284585, 9803145, 12924009, 16736265, 21335145, 26822025, 33304425, 40896009, 49716585, 59892105, 71554665, 84842505, 99900009 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,1

COMMENTS

Sum_{n>=0} 1/a(n) = (3*Pi - 8)/144.

3 divides a(n).

For n=5k, 5k+1, 5k+2 and 5k+3, a(n) is a multiple of 5. For n=5k+4, a(n)-9 is a multiple of 100. - Michel Marcus, Aug 21 2013

LINKS

Table of n, a(n) for n=0..24.

FORMULA

G.f.: 3*(35 + 980*x + 1010*x^2 + 20*x^3 + 3*x^4)/(1-x)^5.

a(n) = (4*n+1)*(4*n+3)*(4*n+5)*(4*n+7).

a(n) = 5*a(n-1) - 10*a(n-2) + 10*a(n-3) - 5*a(n-4) + a(n-5).

PROG

(PARI) a(n) = (4*n+1)*(4*n+3)*(4*n+5)*(4*n+7); \\ Michel Marcus, Aug 21 2013

CROSSREFS

Cf. A133766, A001539, A157142.

Sequence in context: A166803 A262075 A018233 * A122814 A289952 A112490

Adjacent sequences:  A154630 A154631 A154632 * A154634 A154635 A154636

KEYWORD

easy,nonn,changed

AUTHOR

Jaume Oliver Lafont, Jan 13 2009

STATUS

approved

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Last modified September 16 02:16 EDT 2019. Contains 327088 sequences. (Running on oeis4.)