A218148 a(n) = 2^((6+5*n+n^3)/6).

1, 2, 4, 16, 256, 32768, 67108864, 4398046511104, 18446744073709551616, 9903520314283042199192993792, 1361129467683753853853498429727072845824, 95780971304118053647396689196894323976171195136475136

Offset

-1,2

Comments

a(n) = a(0)*product(i = 1..k) r(i)^C(n,i), with C(n,i) = 0 for all i > n. Here, it is submitted a special case of the geometric-geometric sequence having finite ratios, that is, k consecutive rows of ratios, whose first terms are r(1), r(2), r(3), ..., r(k), the last row (k-th row) being of a constant ratio, with k = 3, a(0) = r(1) = r(2) = r(3) = 2.

Links

Table of n, a(n) for n=-1..10.

Formula

a(n) = a(n-1)*(2^(1+n*(n-1)/2)), with a(0)=2.

Maple

A218148:=n->2^((6 + 5*n + n^3)/6); seq(A218148(n), n=-1..10); # Wesley Ivan Hurt, Jan 28 2014

Mathematica

Table[2^((6 + 5*n + n^3)/6), {n, -1, 10}] (* T. D. Noe, Oct 23 2012 *)

Prog

(Maxima) A218148(n):= if n=0 then 2 else 2^((6+5*n+n^3)/6)$ makelist(A218148(n), n, 0, 30); /* Martin Ettl, Oct 24 2012 */

Crossrefs

Cf. A006125.

Sequence in context: A299535 A220169 A178077 * A112535 A001146 A114641

Adjacent sequences: A218145 A218146 A218147 * A218149 A218150 A218151

Keyword

nonn

Author

Mokhtar Mohamed, Oct 22 2012

Status

approved