A288291 Position of the first time an n-digit number appears twice in a row after the decimal point of e.

31, 49, 97, 2, 112869, 5005575, 1561314, 69682897, 1841794338

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..9.

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

a(9) from Michael S. Branicky, Jan 20 2023

Status

approved