A226360 a(n) = smallest triangular number > a(n-1) with a(n-1) as a substring, a(1) = 1.

1, 10, 105, 6105, 6105765, 3761057654628, 291937610576546289190956

Offset

1,2

Comments

Corresponding indices of triangular numbers: 1, 4, 14, 110, 3494, 2742647, 764117282328.

a(8) <= 125453853555414109876348291937610576546289190956. - Giovanni Resta, Jun 05 2013

Links

Table of n, a(n) for n=1..7.

Mathematica

n = 1; t = 1; Print[{n, t}]; Do[ts = ToString[t]; x = n + 1; While[StringFreeQ[ToString[x (x + 1)/2], ts], x++]; Print[{n = x, t = x (x + 1)/2}], {5}]

Crossrefs

Cf. A000217 (triangular numbers).

Sequence in context: A068883 A087599 A337826 * A068097 A190956 A142987

Adjacent sequences: A226357 A226358 A226359 * A226361 A226362 A226363

Keyword

nonn,base

Author

Zak Seidov, Jun 05 2013

Extensions

a(7) from Giovanni Resta, Jun 05 2013

Status

approved