1,1

The number 2 appears in A217916 only in column 1.

The positions of 2 are given by A217919.

Paul D. Hanna, Table of n, a(n) for n = 1..287

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

Cf. A217916, A217918, A217919.

Sequence in context: A060547 A079878 A324469 * A137406 A181293 A262876

Adjacent sequences: A217917 A217918 A217919 * A217921 A217922 A217923

nonn

Paul D. Hanna, Mar 04 2013

approved