1,1

a(n)==0 mod 24. It seems that a(n)==0 (mod 2n+1) if and only if 2n+1 is an odd prime.

Cf. A000203.

Sequence in context: A027260 A125387 A126545 this_sequence A003264 A003272 A003245

Adjacent sequences: A081860 A081861 A081862 this_sequence A081864 A081865 A081866

nonn

Benoit Cloitre (benoit7848c(AT)orange.fr), Apr 12 2003