A259403 Pentagonal numbers (A000326) that are the sum of eleven consecutive pentagonal numbers.

2882, 27676, 1114135, 10982301, 443390277, 4370895551, 176468183540, 1739605414426, 70233893626072, 692358584013426, 27952913194960545, 275556976831896551, 11125189217700638267, 109670984420510781301, 4427797355731659037150, 43648776242386459028676

Offset

1,1

Links

Colin Barker, Table of n, a(n) for n = 1..767

Index entries for linear recurrences with constant coefficients, signature (1,398,-398,-1,1).

Formula

G.f.: -11*x*(16*x^4+14*x^3-5507*x^2+2254*x+262) / ((x-1)*(x^2-20*x+1)*(x^2+20*x+1)).

Example

2882 is in the sequence because P(44) = 2882 = 92 + 117 + 145 + 176 + 210 + 247 + 287 + 330 + 376 + 425 + 477 = P(8)+ ... +P(18).

Mathematica

LinearRecurrence[{1, 398, -398, -1, 1}, {2882, 27676, 1114135, 10982301, 443390277}, 30] (* Harvey P. Dale, Jan 21 2017 *)

Prog

(PARI) Vec(-11*x*(16*x^4+14*x^3-5507*x^2+2254*x+262)/((x-1)*(x^2-20*x+1)*(x^2+20*x+1)) + O(x^20))

Crossrefs

Cf. A000326, A133301, A257714, A257715, A259402, A259404.

Sequence in context: A066407 A184602 A144547 * A241529 A185502 A035895

Adjacent sequences: A259400 A259401 A259402 * A259404 A259405 A259406

Keyword

nonn,easy

Author

Colin Barker, Jun 26 2015

Status

approved