1,1

NE to SW Diagonal of Ulam Spiral, with 101 at center

The sequence does not match the definition. A working definition might be a(2n)=4n^2-10n+107, a(2n-1)=4n^2+2n+101, a(n)=n^2-n+105+2*(-1)^n*(1-2*n), but this seems to be unrelated to Ulam spirals. [From R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Jun 11 2009]

Sequence in context: A160487 A096712 A161176 this_sequence A099652 A118774 A033218

Adjacent sequences: A161369 A161370 A161371 this_sequence A161373 A161374 A161375

nonn

Milton L. Brown (miltbrown(AT)earthlink.net), Jun 08 2009