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Revision History for A217187

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a(n) is the number of digits in the decimal representation of the smallest power of 5 that contains n consecutive identical digits.
(history; published version)

#7 by Harvey P. Dale at Sun Aug 27 14:21:03 EDT 2023

STATUS

editing

approved

#6 by Harvey P. Dale at Sun Aug 27 14:21:01 EDT 2023

MATHEMATICA

Module[{nn=3000, p5}, p5=5^Range[nn]; Table[IntegerLength[SelectFirst[p5, SequenceCount[ IntegerDigits[ #], PadRight[{}, n, x_]]>0&]], {n, 12}]] (* Harvey P. Dale, Aug 27 2023 *)

STATUS

approved

editing

#5 by T. D. Noe at Wed Oct 03 14:51:33 EDT 2012

STATUS

editing

approved

#4 by T. D. Noe at Wed Oct 03 14:51:28 EDT 2012

MATHEMATICA

k = 0; Join[{1}, Table[While[d = IntegerDigits[5^k]; prt = Partition[Differences[d], n - 1, 1]; ! MemberQ[prt, Table[0, {n - 1}]], k++]; Length[d], {n, 2, 8}]] (* T. D. Noe, Oct 03 2012 *)

#3 by V. Raman at Mon Oct 01 07:46:09 EDT 2012

COMMENTS

Number of digits in 5^k is equal to ceilfloor(1 + k*log_10(5)).

#2 by V. Raman at Thu Sep 27 12:31:09 EDT 2012

NAME

allocated for V. Raman

a(n) is the number of digits in the decimal representation of the smallest power of 5 that contains n consecutive identical digits.

DATA

1, 8, 35, 67, 88, 760, 1948, 1951, 1955, 1956, 1959, 1960

OFFSET

1,2

COMMENTS

Number of digits in 5^k is equal to ceil(k*log_10(5)).

CROSSREFS

Cf. A215728, A215734.

KEYWORD

allocated

nonn,base

AUTHOR

V. Raman, Sep 27 2012

STATUS

approved

editing

#1 by V. Raman at Thu Sep 27 12:31:09 EDT 2012

NAME

allocated for V. Raman

KEYWORD

allocated

STATUS

approved