A217162 a(n) is the least value of k such that the decimal expansion of n^k contains seven consecutive identical digits.

972, 2124, 486, 2786, 1503, 1961, 324, 1062, 7, 1323, 1938, 512, 1053, 2600, 243, 2474, 1486, 940, 7, 1085, 1068, 238, 2908, 1393, 699, 708, 704, 1566, 7, 286, 1711, 935, 2225, 1190, 1357, 692, 1182, 448, 7, 885, 1349, 815, 647, 1675, 1131, 548, 333, 1154, 7

Offset

2,1

Links

V. Raman, Table of n, a(n) for n = 2..1000

Mathematica

Table[k = 1; While[! MemberQ[Partition[Differences[IntegerDigits[n^k]], 6, 1], {0, 0, 0, 0, 0, 0}], k++]; k, {n, 2, 100}] (* T. D. Noe, Oct 01 2012 *)
scd[n_]:=Module[{k=1}, While[FreeQ[IntegerDigits[n^k], {___, x_, x_, x_, x_, x_, x_, x_, ___}], k++]; k]; Array[scd, 50, 2] (* Harvey P. Dale, May 23 2016 *)

Crossrefs

Cf. A045875, A215727, A215728, A215729, A215730, A215731.

Sequence in context: A243861 A171771 A206089 * A203375 A183359 A203030

Adjacent sequences: A217159 A217160 A217161 * A217163 A217164 A217165

Keyword

nonn,base

Author

V. Raman, Sep 27 2012

Status

approved