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A095415 Length of repunits of which the prime factor-digit-excess computed by A095414 equals 0. 3
2, 3, 5, 7, 9, 11, 13, 17, 19, 23, 27, 31, 47, 59, 67, 71, 83, 113, 127, 139, 163, 197, 211, 229, 251, 263, 311, 317 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

A004023 is a subsequence. 347, 421, 457, 461, 541, 701, 857 are also terms. Conjecture: Except for the number 4, A046413 is a subsequence. Conjecture: except for the prime powers 9 and 27, all terms are prime. - Chai Wah Wu, Nov 03 2019

LINKS

Table of n, a(n) for n=1..28.

FORMULA

Solutions to A095414(x)=0.

MATHEMATICA

d[1] = -1; d[n_] := Total[ IntegerLength /@ First /@ FactorInteger[(10^n - 1)/9]] - n; Select[ Range[67], d[#] == 0 &] (* Giovanni Resta, Jul 16 2018 *)

CROSSREFS

Cf. A002275, A004023, A095370, A095407, A095413-A095418.

Sequence in context: A070566 A325623 A136327 * A326149 A301987 A316857

Adjacent sequences:  A095412 A095413 A095414 * A095416 A095417 A095418

KEYWORD

nonn,more,base

AUTHOR

Labos Elemer, Jun 22 2004

EXTENSIONS

Data corrected and extended by Giovanni Resta, Jul 16 2018

STATUS

approved

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Last modified May 30 17:10 EDT 2020. Contains 334728 sequences. (Running on oeis4.)