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A213552 Principal diagonal of the convolution array A213551. 3
1, 15, 81, 281, 756, 1722, 3486, 6462, 11187, 18337, 28743, 43407, 63518, 90468, 125868, 171564, 229653, 302499, 392749, 503349, 637560, 798974, 991530, 1219530, 1487655, 1800981, 2164995, 2585611, 3069186, 3622536, 4252952 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

Clark Kimberling, Table of n, a(n) for n = 1..1000

Index entries for linear recurrences with constant coefficients, signature (6,-15,20,-15,6,-1).

FORMULA

a(n) = n*(1 + n)*(2 + n)(-3 + 7*n + 16*n^2)/120.

a(n) = 6*a(n-1) - 15*a(n-2) + 20*a(n-3) - 15*a(n-4) + 6*a(n-5) - a(n-6).

G.f.: x*(1 + 9*x  + 6*x^2)/(1 - x)^6.

MATHEMATICA

(See A213551.)

CROSSREFS

Cf. A213551, A213500.

Sequence in context: A102360 A309336 A266288 * A060581 A253222 A284900

Adjacent sequences:  A213549 A213550 A213551 * A213553 A213554 A213555

KEYWORD

nonn,easy

AUTHOR

Clark Kimberling, Jun 17 2012

STATUS

approved

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Last modified January 25 23:04 EST 2020. Contains 331270 sequences. (Running on oeis4.)