Triangular numbers in which neighboring digits differ at most by 1. Allowed neighbors of 9 are 0, 8 and 9.

A068149

Triangular numbers in which neighboring digits differ at most by 1. Allowed neighbors of 9 are 0, 8 and 9.

Terms

    a(0) =0a(1) =1a(2) =3a(3) =6a(4) =10a(5) =21a(6) =45a(7) =55a(8) =66a(9) =78a(10) =210a(11) =666a(12) =990a(13) =2211a(14) =3321a(15) =5565a(16) =6555a(17) =8778a(18) =10011a(19) =90100a(20) =112101a(21) =222111a(22) =232221a(23) =443211a(24) =887778a(25) =5433456a(26) =5456556a(27) =5656566a(28) =5676765a(29) =22221111

External references