A119220 Triangular numbers composed of digits {5,6,8}.

6, 55, 66, 666, 5565, 5886, 6555, 866586, 5656566, 5566865886, 58855888686, 866856686865, 6686866555566, 56588686866855, 88588558556655, 555665666566566, 685565588888866, 656585655585666885, 5866665855856865856556555656, 5555555666655656666556566566566, 5588888688855688866886555588568586

Offset: 1

Author

Giovanni Resta, May 10 2006

Keywords

• nonn
• base

Comments

All terms except the first end in 55, 56, 65, 66, 85 or 86. - Robert Israel, Mar 26 2023

Links

• Giovanni Resta, Tridigital Triangular Numbers.

Crossrefs

Cf. A000217, A119221. See A119033 for a table of cross-references.

Formula

a(n) = A000217(A119221(n)). - Tyler Busby, Mar 26 2023

Extensions

a(19)-a(21) from Tyler Busby, Mar 26 2023