Sigma-decagonal numbers: numbers k such that sigma(k) is a decagonal number, that is, sigma(k) = 4*m^2 - 3*m for some nonnegative integer m.

A180937

Sigma-decagonal numbers: numbers k such that sigma(k) is a decagonal number, that is, sigma(k) = 4*m^2 - 3*m for some nonnegative integer m.

Terms

    a(0) =1a(1) =68a(2) =82a(3) =290a(4) =358a(5) =392a(6) =445a(7) =493a(8) =816a(9) =880a(10) =1024a(11) =1136a(12) =1150a(13) =1224a(14) =1275a(15) =1296a(16) =1342a(17) =1417a(18) =1486a(19) =1602a(20) =1671a(21) =1775a(22) =1864a(23) =2025a(24) =2421a(25) =2810a(26) =3180a(27) =3488a(28) =3493a(29) =3680

External references