Numbers k such that the k-th centered 40-gonal numbers (A195317) is a square.

A351354

Numbers k such that the k-th centered 40-gonal numbers (A195317) is a square.

Terms

    a(0) =1a(1) =3a(2) =7a(3) =45a(4) =117a(5) =799a(6) =2091a(7) =14329a(8) =37513a(9) =257115a(10) =673135a(11) =4613733a(12) =12078909a(13) =82790071a(14) =216747219a(15) =1485607537a(16) =3889371025a(17) =26658145587a(18) =69791931223a(19) =478361013021

External references