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A123613 Column 3 of triangle A123610. 5
1, 4, 20, 68, 175, 392, 786, 1440, 2475, 4036, 6292, 9464, 13805, 19600, 27200, 36996, 49419, 64980, 84238, 107800, 136367, 170696, 211600, 260000, 316881, 383292, 460404, 549460, 651775, 768800, 902066, 1053184, 1223915, 1416108, 1631700, 1872792, 2141581 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

LINKS

G. C. Greubel, Table of n, a(n) for n = 0..1000

Index entries for linear recurrences with constant coefficients, signature (4,-6,6,-9,12,-9,6,-6,4,-1).

FORMULA

G.f.: P_3(x) / ((1-x)^2*(1-x^2)^2*(1-x^3)^2), with P_3(1) = 5!, where P_3(x) = (1+2*x+11*x^2+26*x^3+30*x^4+26*x^5+17*x^6+6*x^7+x^8).

MATHEMATICA

CoefficientList[Series[(1 + 2*x + 11*x^2 + 26*x^3 + 30*x^4 + 26*x^5 + 17*x^6 + 6*x^7 + x^8)/((1 - x)^2*(1 - x^2)^2*(1 - x^3)^2), {x, 0, 50}], x] (* G. C. Greubel, Oct 16 2017 *)

LinearRecurrence[{4, -6, 6, -9, 12, -9, 6, -6, 4, -1}, {1, 4, 20, 68, 175, 392, 786, 1440, 2475, 4036}, 40] (* Harvey P. Dale, Apr 22 2019 *)

PROG

(PARI) {a(n)=polcoeff(truncate(Ser([1, 2, 11, 26, 30, 26, 17, 6, 1]))/((1-x)^2*(1-x^2)^2*(1-x^3)^2 +x*O(x^n)), n)}

CROSSREFS

Cf. A123610 (triangle); columns: A005997, A123614, A123615, A123616.

Sequence in context: A319779 A287244 A344993 * A006740 A291526 A303011

Adjacent sequences:  A123610 A123611 A123612 * A123614 A123615 A123616

KEYWORD

nonn,easy

AUTHOR

Paul D. Hanna, Oct 03 2006

STATUS

approved

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Last modified June 29 18:25 EDT 2022. Contains 354913 sequences. (Running on oeis4.)