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A030280 COMPOSE triangular numbers with triangular numbers. 5
1, 6, 30, 137, 588, 2415, 9600, 37209, 141336, 528049, 1945800, 7086555, 25550547, 91319973, 323890062, 1140985116, 3995155506, 13913280006, 48216776266, 166355744244, 571636515369, 1957015021744, 6677155551312 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

Harvey P. Dale, Table of n, a(n) for n = 1..1000

N. J. A. Sloane, Transforms

Index entries for linear recurrences with constant coefficients, signature (12, -57, 139, -195, 174, -102, 39, -9, 1).

FORMULA

G.f.: [(1-x)^6]/[(1-4x+3x^2-x^3)^3].

a(1)=1, a(2)=6, a(3)=30, a(4)=137, a(5)=588, a(6)=2415, a(7)=9600, a(8)=37209, a(9)=141336, a(n)=12*a(n-1)-57*a(n-2)+139*a(n-3)- 195*a(n-4)+ 174*a(n-5)-102*a(n-6)+39*a(n-7)-9*a(n-8)+a(n-9). - Harvey P. Dale, Jan 08 2013

MATHEMATICA

CoefficientList[Series[((1-x)^6)/((1-4x+3x^2-x^3)^3), {x, 0, 30}], x] (* or *) LinearRecurrence[{12, -57, 139, -195, 174, -102, 39, -9, 1}, {1, 6, 30, 137, 588, 2415, 9600, 37209, 141336}, 30] (* Harvey P. Dale, Jan 08 2013 *)

CROSSREFS

Sequence in context: A162743 A224290 A081895 * A034545 A002920 A255463

Adjacent sequences:  A030277 A030278 A030279 * A030281 A030282 A030283

KEYWORD

nonn,nice

AUTHOR

Christian G. Bower

STATUS

approved

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Last modified April 19 04:19 EDT 2019. Contains 322237 sequences. (Running on oeis4.)