1,2

Equivalently, this sequences is a list of indices i such that A271328(i) != i^2 + 1.

If k is in A271328, then k is in this sequence.

All multiples of a(k) are in the sequence for k > 1.

Peter Kagey, Table of n, a(n) for n = 1..10000

A269347(3*1) = 3 != 3*(1^2 + 1) = 6 so 1 is in the sequence.

A269347(3*2) = 15 = 3*(2^2 + 1) so 2 is not in the sequence.

A269347(3*3) = 30 = 3*(3^2 + 1) so 3 is not in the sequence.

A269347(3*4) = 51 = 3*(4^2 + 1) so 4 is not in the sequence.

A269347(3*5) = 84 != 3*(5^2 + 1) = 78 so 5 is in the sequence.

Sequence in context: A236848 A236835 A236844 * A313669 A254063 A313670

Adjacent sequences: A271465 A271466 A271467 * A271469 A271470 A271471

nonn

Peter Kagey, Apr 08 2016

approved