OFFSET
1,15
LINKS
Eric Weisstein's World of Mathematics, Goldbach Partition
Wikipedia, Goldbach's conjecture
FORMULA
EXAMPLE
a(15) = 2; There are 2 Goldbach partitions of 2*15 = 30 where the smaller part is an even-indexed prime and the larger part is an odd-indexed prime: (23,7) and (17,13). For example, 23 is the 9th prime and 7 is the 4th prime, while 17 is the 7th prime and 13 is the 6th prime.
MATHEMATICA
Table[Sum[Mod[PrimePi[k] + 1, 2] Mod[PrimePi[2 n - k], 2] (PrimePi[k] - PrimePi[k - 1]) (PrimePi[2 n - k] - PrimePi[2 n - k - 1]), {k, n}], {n, 100}]
CROSSREFS
KEYWORD
nonn
AUTHOR
Wesley Ivan Hurt, Jun 04 2021
STATUS
approved