OFFSET
0,7
LINKS
Eric Weisstein's World of Mathematics, Twin Primes
FORMULA
a(n) = [x^(2*n)] Product_{k>=1} 1/(1 - x^A014574(k)).
EXAMPLE
a(10) = 3 because we have [12, 4, 4], [6, 6, 4, 4] and [4, 4, 4, 4, 4].
MATHEMATICA
nmax = 65; Table[CoefficientList[Series[Product[1/(1 - Boole[PrimeQ[k + 1] && PrimeQ[k - 1]] x^k), {k, 1, 2 nmax}], {x, 0, 2 nmax}], x][[n]], {n, 1, 2 nmax + 1, 2}]
CROSSREFS
KEYWORD
nonn
AUTHOR
Ilya Gutkovskiy, Oct 25 2018
STATUS
approved