A166119 a(n) = A165966(n)/12.
3, 10, 23, 25, 213, 270, 455, 688, 1060, 1953, 2233, 2915, 3468, 3838, 4718, 4945, 8645, 10230, 11638, 12308, 13090, 15428, 16250, 19295, 23095, 27778, 29435, 32230, 33488, 43053, 50830, 71668, 83485, 86460, 89365, 96330, 104610, 106600, 127823
Offset: 1
Keywords
Programs
-
PARI
lista(nn) = {for (n = 1, nn, trg = n*(n+1)/2; if (!(trg % 2) && isprime(trg/2-1) && isprime(trg/2+1), print1(trg/12, ", ")););} \\ Michel Marcus, Oct 16 2013
Formula
a(n) = (A086816(n) + 1)/6. - Alois P. Heinz, Sep 18 2024
Comments