OFFSET
1,2
FORMULA
a(n) = Sum_{k=1..n} binomial(prime(k) + n-k-1, n-k).
EXAMPLE
G.f.: A(x) = x + 3*x^2 + 7*x^3 + 16*x^4 + 38*x^5 + 96*x^6 + 262*x^7 + 767*x^8 +...
where
A(x) = x/(1-x)^2 + x^2/(1-x)^3 + x^3/(1-x)^5 + x^4/(1-x)^7 + x^5/(1-x)^11 + x^6/(1-x)^13 + x^7/(1-x)^17 + x^8/(1-x)^19 +...+ x^n/(1-x)^prime(n) +...
PROG
(PARI) {a(n)=polcoeff(sum(m=1, n, x^m/(1-x+x*O(x^n))^prime(m)), n)}
for(n=1, 40, print1(a(n), ", "))
(PARI) {a(n) = sum(k=1, n, binomial(prime(k)+n-k-1, n-k))}
for(n=1, 40, print1(a(n), ", "))
CROSSREFS
KEYWORD
nonn
AUTHOR
Paul D. Hanna, Jul 14 2013
STATUS
approved