A131548 Least power of 3 having exactly n consecutive 5's in its decimal representation.

8, 27, 39, 33, 274, 2076, 5173, 8880, 67390, 206131, 864271, 1291676, 5756979, 13654248, 73000220

Offset

1,1

Links

Table of n, a(n) for n=1..15.

Example

a(3)=39 because 3^39(i.e. 4052555153018976267) is the smallest power of 3 to contain a run of 3 consecutive fives in its decimal form.

Mathematica

a = ""; Do[ a = StringJoin[a, "5"]; b = StringJoin[a, "5"]; k = 1; While[ StringPosition[ ToString[3^k], a] == {} || StringPosition[ ToString[3^k], b] != {}, k++ ]; Print[k], {n, 1, 10} ]

Crossrefs

Cf. A195269, A131552, A131551, A131550, A131549, A131547, A131546, A131545, A131544.

Sequence in context: A066215 A086213 A175050 * A063142 A235994 A144619

Adjacent sequences: A131545 A131546 A131547 * A131549 A131550 A131551

Keyword

more,nonn,base

Author

Shyam Sunder Gupta, Aug 26 2007

Extensions

a(11)-a(14) from Lars Blomberg, Feb 02 2013

a(15) from Bert Dobbelaere, Mar 05 2019

Status

approved