OFFSET
0,2
COMMENTS
Indices of noncomposite terms are 0, 1, 2, 4, 5, 8, 43, 127, 251, ...
FORMULA
a(n) = A076793(n) + 1.
MATHEMATICA
Join[{1}, Accumulate[2^Prime[Range[30]]]+1] (* Harvey P. Dale, Mar 26 2019 *)
PROG
(PARI) apply( A320877(n)=1+sum(k=1, n, 2^prime(k)), [0..30])
CROSSREFS
KEYWORD
nonn
AUTHOR
M. F. Hasler, Oct 30 2018
STATUS
approved