A069601 Smallest triangular number containing all the digits of numbers from 1 to n.

1, 21, 231, 12403, 24531, 235641, 2467531, 13862745, 153694278, 10429651378, 1017139458621, 101114872391625, 10111496127133528, 1011137441915312286, 101111293764315411825, 10111111491815764232356, 1011111155214617733491628, 101111111617874325294116835

Offset

1,2

Comments

For a(10) and higher, all duplicated digits must be in the term (for example a(10) has two 1's).

Conjecture: except for a(4), the digits of a(n) are exactly all the digits of numbers from 1 to n. - Chai Wah Wu, May 18 2020

Links

Chai Wah Wu, Table of n, a(n) for n = 1..29

Example

a(5) = 219453 = T(662) contains digits 1, 2, 3, 4 and 5.

Crossrefs

Cf. A088628, A069600.

Sequence in context: A125409 A161581 A350570 * A173347 A360854 A303968

Adjacent sequences: A069598 A069599 A069600 * A069602 A069603 A069604

Keyword

nonn,base

Author

Amarnath Murthy, Mar 25 2002

Extensions

Corrected and extended by Larry Reeves (larryr(AT)acm.org), Jan 24 2003

a(15)-a(18) from Chai Wah Wu, May 18 2020

Status

approved