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A288291 Position of the first time an n-digit number appears twice in a row after the decimal point of e. 2
31, 49, 97, 2, 112869, 5005575, 1561314, 69682897 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

18281828 appears in e before any 1-digit, 2-digit, or 3-digit number appears twice in a row.

LINKS

Table of n, a(n) for n=1..8.

EXAMPLE

a(1) = 31 because the first time a 1-digit number appears twice in a row in the decimal expansion of e is 31 digits after the decimal point: 2.718281828459045235360287471352(66)...

MATHEMATICA

s = First@ RealDigits[E, 10, 51*^5]; Table[p = Partition[s, k, 1];

SelectFirst[ Range[ Length[p] - k], p[[#]] == p[[# + k]] &] - 1, {k, 7}] (* Giovanni Resta, Sep 05 2017 *)

CROSSREFS

Cf. A001113, A287994, A290984.

Sequence in context: A244601 A004224 A194129 * A248904 A068779 A068473

Adjacent sequences:  A288288 A288289 A288290 * A288292 A288293 A288294

KEYWORD

nonn,base,more

AUTHOR

Bobby Jacobs, Sep 01 2017

EXTENSIONS

a(6)-a(8) from Giovanni Resta, Sep 05 2017

STATUS

approved

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Last modified August 10 04:38 EDT 2020. Contains 336368 sequences. (Running on oeis4.)