OFFSET
1,2
REFERENCES
L. Comtet, Advanced Combinatorics, Reidel, 1974, p. 91, #42.
LINKS
Harry J. Smith, Table of n, a(n) for n = 1..12
FORMULA
a(n) = Sum_{k=0..n-1} binomial(n,k)*2^(2^k-1).
a(n) ~ n * 2^(2^(n-1)-1). - Vaclav Kotesovec, Nov 27 2017
MATHEMATICA
Table[Sum[Binomial[n, k]*2^(2^k - 1), {k, 0, n - 1}], {n, 1, 10}] (* G. C. Greubel, Jan 06 2017 *)
PROG
(PARI) { for (n = 1, 12, a=0; for (k=0, n-1, a+=binomial(n, k)*2^(2^k - 1); ); write("b059301.txt", n, " ", a); ) } \\ Harry J. Smith, Jun 25 2009
(PARI) a(n) = sum(k=0, n-1, binomial(n, k)*2^(2^k-1)); \\ Michel Marcus, Jan 03 2016
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
N. J. A. Sloane, Jan 26 2001
STATUS
approved