A217919 Rows of A217916 in which 2's appear, when A217916 is formed into a number triangle.

1, 3, 5, 8, 10, 16, 19, 20, 23, 51, 54, 58, 70, 71, 103, 136, 139, 142, 145, 153, 161, 168, 169, 182, 204, 212, 219, 222, 224, 230, 232, 235, 240, 242, 276, 277, 286

Offset: 1

Author

Paul D. Hanna, Mar 04 2013

Keywords

• nonn

Comments

The number 2 appears only in column 1 of A217916 (when treated as a triangle).

Crossrefs

Cf. A217916, A217918.

Formula

Involves triangular-indexed twin primes:

prime(a(n)*(a(n)-1)/2 + 1) - prime(a(n)*(a(n)-1)/2) = 2 for n>1 with a(1)=1.