1,1

Amiram Eldar, Table of n, a(n) for n = 1..10000

a(n) = A033880(A111592(n))/2 = A111667(n)/2. - Amiram Eldar, Jun 22 2019

a(1)=2 because 12 = 1+3+4+6-2, the 2 is subtracted. a(6)=6 because 42 = 1+2+3+7+14+21-6, the 6 is subtracted.

Cf. A033880, A111592, A111667.

Sequence in context: A193561 A328349 A117965 * A342965 A117753 A145883

Adjacent sequences: A111643 A111644 A111645 * A111647 A111648 A111649

easy,nonn

Jason Earls, Aug 10 2005

approved