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A259402 Pentagonal numbers (A000326) that are the sum of seven consecutive pentagonal numbers. 5
287, 532, 17145051, 32963672, 1106094475927, 2126616990876, 71358579001465427, 137196568515066592, 4603627364594444737551, 8851099419054387781412, 296998415728087428795555787, 571019827783678204813603176, 19160555787678205016722039960967 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Colin Barker, Table of n, a(n) for n = 1..416

Index entries for linear recurrences with constant coefficients, signature (1,64514,-64514,-1,1).

FORMULA

G.f.: -7*x*(1968*x^4+1813*x^3-195857*x^2+35*x+41) / ((x-1)*(x^2-254*x+1)*(x^2+254*x+1)).

EXAMPLE

287 is in the sequence because P(14) = 287 = 5+12+22+35+51+70+92 = P(2)+ ... +P(8).

PROG

(PARI) Vec(-7*x*(1968*x^4+1813*x^3-195857*x^2+35*x+41)/((x-1)*(x^2-254*x+1)*(x^2+254*x+1)) + O(x^20))

CROSSREFS

Cf. A000326, A133301, A257714, A257715, A259403, A259404.

Sequence in context: A295447 A203049 A306788 * A157997 A063362 A159949

Adjacent sequences:  A259399 A259400 A259401 * A259403 A259404 A259405

KEYWORD

nonn,easy

AUTHOR

Colin Barker, Jun 26 2015

STATUS

approved

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Last modified June 3 03:59 EDT 2020. Contains 334793 sequences. (Running on oeis4.)