A131550 a(n) is the least exponent e such that 3^e has exactly n consecutive 3's in its decimal representation.

1, 31, 119, 185, 511, 2341, 9671, 7721, 67449, 364579, 513334, 639227, 6250772, 30377688, 82011443, 78927181

Offset: 1

Author

Shyam Sunder Gupta, Aug 26 2007

Keywords

• more
• nonn
• base

Comments

No more terms < 10^8. - Bert Dobbelaere, Mar 20 2019

Examples

			a(3)=119 because 3^119 (i.e., 599003433304810403471059943169868346577158542512617035467) is the smallest power of 3 to contain a run of 3 consecutive threes in its decimal form.
		

Crossrefs

Cf. A195269, A131552, A131551, A131549, A131548, A131547, A131546, A131545, A131544.

Programs

Mathematica

a = ""; Do[ a = StringJoin[a, "3"]; b = StringJoin[a, "3"]; k = 1; While[ StringPosition[ ToString[3^k], a] == {} || StringPosition[ ToString[3^k], b] != {}, k++ ]; Print[k], {n, 1, 10} ]

Extensions

a(11)-a(13) from Lars Blomberg, Feb 02 2013

a(14)-a(16) from Bert Dobbelaere, Mar 20 2019