OFFSET
4,1
LINKS
Alois P. Heinz, Table of n, a(n) for n = 4..500
FORMULA
E.g.f.: A(A(x)) where A(x) = Sum_{p=prime} x^p/p!.
MAPLE
with(combinat): with(numtheory):
b:= proc(n, i, m) option remember; `if`(n=0, `if`(isprime(m), 1, 0),
`if`(i<1, 0, (p-> add(multinomial(n, n-p*j, p$j)/j!*
b(n-p*j, i-1, m+j), j=0..n/p))(ithprime(i))))
end:
a:= n-> b(n, pi(n), 0):
seq(a(n), n=4..30); # Alois P. Heinz, Sep 17 2015
MATHEMATICA
a= Table[Prime[n], {n, 1, 25}]; b[x_]:= Sum[x^i/i!, {i, a}]; Range[0, 25]! CoefficientList[Series[b[b[x]], {x, 0, 25}], x]
CROSSREFS
KEYWORD
nonn
AUTHOR
Geoffrey Critzer, May 11 2011
STATUS
approved