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A131552 Least positive power of 3 having exactly n consecutive 1's in its decimal representation. 2
4, 19, 93, 334, 841, 3404, 7271, 7720, 44152, 406774, 993948, 2421339, 8786439, 11387707 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

No more terms < 2*10^7.

LINKS

Table of n, a(n) for n=1..14.

EXAMPLE

a(3)=93 because 3^93 (i.e., 235655016338368235499067731945871638181119123) is the smallest power of 3 to contain a run of 3 consecutive ones in its decimal form.

MATHEMATICA

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

PROG

(Python)

def A131552(n):

....m, s = 1, '1'*n

....for i in range(1, 10**9):

........m *= 3

........if s in str(m):

............return i

....return "search limit reached." # Chai Wah Wu, Dec 11 2014

CROSSREFS

Sequence in context: A181950 A288687 A275751 * A122369 A005978 A083065

Adjacent sequences:  A131549 A131550 A131551 * A131553 A131554 A131555

KEYWORD

more,nonn,base

AUTHOR

Shyam Sunder Gupta, Aug 26 2007

EXTENSIONS

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

Definition edited by Chai Wah Wu, Dec 11 2014

STATUS

approved

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Last modified December 15 13:27 EST 2018. Contains 318149 sequences. (Running on oeis4.)