A119204 Triangular numbers composed of digits {4,5,7}.

45, 55, 5747745, 744574755, 77545447574475, 4745745457757444544544575, 44477447457545755547775754555, 547457575775574544754447747777455

Offset: 1

Author

Giovanni Resta, May 10 2006

Keywords

• nonn
• base
• more

Comments

a(8) > 10^40. - Tyler Busby, Mar 28 2023

Links

• Giovanni Resta, Tridigital Triangular Numbers.

Crossrefs

Cf. A000217, A053951, A119205. See A119033 for a table of cross-references.

Formula

a(n) = A000217(A119205(n)). - Jon E. Schoenfield, Mar 27 2023

Extensions

a(8) from Tyler Busby, Mar 28 2023