A254502 a(n) is the smallest nonnegative integer such that a(n)! contains a string of exactly n consecutive 7's.
0, 6, 31, 48, 22, 599, 1102, 5280, 4667, 1753, 48861, 150336, 223254, 644487, 7016773, 9588848
Offset: 0
Examples
a(1) = 6 since 6! equals 720, which contains '7'.
Programs
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Mathematica
A254452[n_] := Module[{m = 0}, If[n == 0, While[MemberQ[IntegerDigits[m!], 7], m++]; m, t = Table[7, n]; While[! MemberQ[Split[IntegerDigits[m!]], t], m++]; m]]; Table[A254452[n], {n, 0, 14}] (* Robert Price, Mar 21 2019 *)
Extensions
a(11), a(12) from Jon E. Schoenfield, Feb 21 2015
a(0) prepended by Jon E. Schoenfield, Mar 01 2015
a(13) from Jon E. Schoenfield, Mar 06 2015
a(14)-a(15) from Bert Dobbelaere, Oct 29 2018