A056589 - OEIS

A056589

Third column sequence of unsigned triangle A056588.

1, 4, 16, 53, 166, 492, 1413, 3960, 10912, 29689, 80026, 214196, 570289, 1512300, 3998160, 10545741, 27766942, 73012060, 191785165, 503378480, 1320425536, 3462057009, 9074076786, 23776857828, 62289901081, 163159711492

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OFFSET

0,2

LINKS

Table of n, a(n) for n=0..25.

FORMULA

a(n)= -A056588(n+2, 2), n >= 0. a(n)= -2^(n+3)+F(n+4)*(F(n+3)+1), F(n)=A000045(n).

G.f.(1-x+x^2)/((1-2*x)*(1+x)*(1-3*x+x^2)*(1-x-x^2))

CROSSREFS

Cf. A000045, A056588, A000012, A000071.

Sequence in context: A232399 A223711 A074409 * A074407 A192074 A293884

Adjacent sequences: A056586 A056587 A056588 * A056590 A056591 A056592

KEYWORD

nonn,easy

AUTHOR

Wolfdieter Lang Jul 10 2000

STATUS

approved