A119075 Triangular numbers composed of digits {0,4,8}.

80080840, 4448084040, 804844884480, 4448404804004804800840804848000, 44804084840840840848040408400000

Offset: 1

Author

Giovanni Resta, May 10 2006

Keywords

• nonn
• base
• more

Comments

a(6) > 10^37. - Max Alekseyev, May 17 2009

a(6) > 10^40. - Tyler Busby, Mar 28 2023

Links

• Giovanni Resta, Tridigital Triangular Numbers.

Crossrefs

Cf. A000217, A058442, A119076. See A119033 for a table of cross-references.

Programs

Magma

[t: n in [1..2*10^7] | Set(Intseq(t)) subset {0, 4, 8} where t is n*(n+1) div 2]; // Vincenzo Librandi, Dec 18 2015

Mathematica

Rest[Select[FromDigits/@Tuples[{0, 4, 8}, 12], IntegerQ[(Sqrt[8 # + 1] - 1)/2] &]] (* Vincenzo Librandi, Dec 18 2015 *)

Formula

a(n) = A000217(A119076(n)). - Michel Marcus, Mar 27 2023