OFFSET
0,32
LINKS
Eric Weisstein's World of Mathematics, Twin Primes
FORMULA
G.f.: Product_{k>=1} (1 + x^A006512(k)).
EXAMPLE
a(31) = 2 because we have [31] and [19, 7, 5].
MATHEMATICA
nmax = 105; CoefficientList[Series[Product[1 + Boole[PrimeQ[k] && PrimeQ[k - 2]] x^k, {k, 1, nmax}], {x, 0, nmax}], x]
CROSSREFS
KEYWORD
nonn
AUTHOR
Ilya Gutkovskiy, Feb 04 2018
STATUS
approved