1,2

Also a triangular number -- follows from the definition of A007501.

a(n)=T(x(n-1))-x(n-1) where x(n)=T(x(n-1)) and T(x)=x*(x+1)/2.

a(1)=T(2)-2

a(2)=T(3)-3

a(3)=T(6)-6

A007501: First differences of successive terms of sequence A007501.

Sequence in context: A166359 A003505 A120601 this_sequence A117820 A126453 A007081

Adjacent sequences: A145269 A145270 A145271 this_sequence A145273 A145274 A145275

easy,nonn

Greg Huber (huber(AT)alum.mit.edu), Oct 06 2008