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A259413 Triangular numbers (A000217) that are the sum of eleven consecutive triangular numbers. 6
2145, 3916, 7381, 13530, 843051, 1547920, 2926990, 5374281, 335521560, 616057651, 1164924046, 2138939715, 133536727236, 245189386585, 463636832725, 851292621696, 53147281907775, 97584759792586, 184526294489911, 338812324484700, 21152484662556621 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Colin Barker, Table of n, a(n) for n = 1..1000

Index entries for linear recurrences with constant coefficients, signature (1,0,0,398,-398,0,0,-1,1).

FORMULA

G.f.: -11*x*(6*x^8-x^7+x^5-2199*x^4+559*x^3+315*x^2+161*x+195) / ((x-1)*(x^4-20*x^2+1)*(x^4+20*x^2+1)).

EXAMPLE

2145 is in the sequence because T(65) = 2145 = 105 + 120 + 136 + 153 + 171 + 190 + 210 + 231 + 253 + 276 + 300 = T(14) + ... + T(24).

MATHEMATICA

LinearRecurrence[{1, 0, 0, 398, -398, 0, 0, -1, 1}, {2145, 3916, 7381, 13530, 843051, 1547920, 2926990, 5374281, 335521560}, 30] (* Vincenzo Librandi, Jun 27 2015 *)

PROG

(PARI) Vec(-11*x*(6*x^8-x^7+x^5-2199*x^4+559*x^3+315*x^2+161*x+195)/((x-1)*(x^4-20*x^2+1)*(x^4+20*x^2+1)) + O(x^30))

CROSSREFS

Cf. A000217, A001110, A129803, A131557, A257711, A257712, A257713, A259414, A259415.

Sequence in context: A200145 A179271 A118576 * A294751 A251893 A251870

Adjacent sequences:  A259410 A259411 A259412 * A259414 A259415 A259416

KEYWORD

nonn,easy

AUTHOR

Colin Barker, Jun 26 2015

STATUS

approved

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Last modified April 4 21:38 EDT 2020. Contains 333238 sequences. (Running on oeis4.)