OFFSET
0,2
FORMULA
G.f.: sqrt( Sum_{n>=0} index of prime a(n+1) * x^n ).
MATHEMATICA
a[0] = 1; a[n_] := a[n] = Prime[Sum[a[k] a[n - k - 1], {k, 0, n - 1}]]; Table[a[n], {n, 0, 11}]
CROSSREFS
KEYWORD
nonn,hard,more
AUTHOR
Ilya Gutkovskiy, Jun 13 2023
EXTENSIONS
a(12)-a(13) from Amiram Eldar, Jun 13 2023
STATUS
approved