OFFSET
0,2
LINKS
Vaclav Kotesovec, Table of n, a(n) for n = 0..1000
FORMULA
a(n) ~ c * 4^n, where c = Product_{m>=2} 1/(1 - m/4^(m-1)) = 2.700170514502619666262858845683166558216386190684736249639219328278569...
MAPLE
b:= proc(n, i) option remember; `if`(n=0 or i=1,
4^n, b(n, i-1) +i*4*b(n-i, min(n-i, i)))
end:
a:= n-> b(n$2):
seq(a(n), n=0..32); # Alois P. Heinz, Aug 23 2019
MATHEMATICA
nmax=40; CoefficientList[Series[Product[1/(1-4*k*x^k), {k, 1, nmax}], {x, 0, nmax}], x]
CROSSREFS
KEYWORD
nonn
AUTHOR
Vaclav Kotesovec, Dec 19 2015
STATUS
approved