A142703 a(n) = 2*(n-1)*( a(n-1)+a(n-2) ) starting a(1)=a(2)=1.

1, 1, 8, 54, 496, 5500, 71952, 1084328, 18500480, 352526544, 7420540480, 171007474528, 4282272360192, 115785275702720, 3361891345761536, 104330298643927680, 3446150079670054912, 120716332862675408128

Offset

1,3

Links

Table of n, a(n) for n=1..18.

Maple

A142703 := proc(n) if n <=2 then 1 ; else 2*(n-1)*( procname(n-1)+procname(n-2)) ; end if; end proc: # R. J. Mathar, May 26 2011

Mathematica

Clear[a, b, n, k] k = 2; b[0] = 0; b[n_] := b[n] = b[n - 1] + k; a[0] = 1; a[1] = 1; a[n_] := a[n] = b[n]*(a[n - 1] + a[n - 2]); Table[a[n], {n, 0, 20}]

Crossrefs

Cf. A002467, A000045.

Sequence in context: A079754 A347274 A298985 * A138403 A013499 A134825

Adjacent sequences: A142700 A142701 A142702 * A142704 A142705 A142706

Keyword

nonn,easy

Author

Roger L. Bagula and Gary W. Adamson, Sep 24 2008

Status

approved