OFFSET
1,3
COMMENTS
LINKS
Zhi-Wei Sun, Table of n, a(n) for n = 1..7000
EXAMPLE
a(23) = 1 since 23 = 9 + 14 with 2^9 + 14*15/2 = 617 prime.
a(64) = 1 since 64 = 14 + 50 with 2^{14} + 50*51/2 = 17659 prime.
MATHEMATICA
a[n_]:=Sum[If[PrimeQ[2^x+(n-x)(n-x+1)/2], 1, 0], {x, 1, n-1}]
Table[a[n], {n, 1, 100}]
CROSSREFS
KEYWORD
nonn
AUTHOR
Zhi-Wei Sun, Nov 11 2013
STATUS
approved