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A112502 Third column of triangle A112500. 2
1, 10, 60, 282, 1149, 4272, 14932, 49996, 162369, 515886, 1613316, 4987542, 15290461, 46592452, 141350412, 427459320, 1289718225, 3884883570, 11688205420, 35135919730, 105558754461, 316995030840, 951656181540 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

COMMENTS

For a combinatorial formula see A112500, case k=3.

LINKS

Table of n, a(n) for n=0..22.

FORMULA

G.f.: 1/product((1-j*x)^(4-j), j=1..3) = 1/(((1-x)^3)*((1-2*x)^2)*(1-3*x)).

a(n) = - 81/8 - (11/4)*(n+1) - (1/2)*binomial(n+2, 2) - 16*(n+1)*2^n + (243/8)*3^n, n>=0 (from partial fractions for g.f.).

CROSSREFS

Cf. A000295 (second column).

Sequence in context: A278721 A004406 A003472 * A293081 A292489 A083585

Adjacent sequences:  A112499 A112500 A112501 * A112503 A112504 A112505

KEYWORD

nonn,easy

AUTHOR

Wolfdieter Lang, Oct 14 2005

STATUS

approved

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Last modified March 20 05:17 EDT 2019. Contains 321344 sequences. (Running on oeis4.)