A217920 - OEIS

%I #6 Mar 06 2013 00:33:31

%S 2,1,2,4,2,6,6,2,6,2,6,14,4,12,6,2,4,4,2,2,6,6,2,4,6,8,6,16,6,4,6,6,6,

%T 6,6,6,14,6,6,14,10,10,8,4,12,20,8,12,6,10,2,6,14,2,14,18,6,2,6,12,4,

%U 28,6,20,6,6,6,4,16,2,2,6,4,12,6,6,6,6,8,4,6,8,6

%N Column 1 of A217916 (when formed into a number triangle).

%C The number 2 appears in A217916 only in column 1.

%C The positions of 2 are given by A217919.

%H Paul D. Hanna, <a href="/A217920/b217920.txt">Table of n, a(n) for n = 1..287</a>

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

%Y Cf. A217916, A217918, A217919.

%K nonn

%O 1,1

%A _Paul D. Hanna_, Mar 04 2013