A119107 Triangular numbers composed of digits {1,2,8}.

1, 21, 28, 1128, 2211, 8128, 118828, 222111, 821121, 828828, 881128, 1188111, 1828828, 22221111, 28218828, 88811128, 1821212128, 2222211111, 8888111128, 222222111111, 888881111128, 22222221111111, 88888811111128, 1122211112118111, 2222222211111111

Offset

1,2

Links

Table of n, a(n) for n=1..25.

Giovanni Resta, Tridigital Triangular Numbers

Formula

a(n) = A000217(A119108(n)). - Michel Marcus, Mar 23 2023

Crossrefs

Cf. A000217, A053887, A119108. See A119033 for a table of cross-references.

Sequence in context: A344603 A212192 A166647 * A004196 A211253 A209975

Adjacent sequences: A119104 A119105 A119106 * A119108 A119109 A119110

Keyword

nonn,base

Author

Giovanni Resta, May 10 2006

Extensions

a(24)-a(25) from Tyler Busby, Mar 23 2023

Status

approved