a(n) is the smallest nonnegative integer such that a(n)! contains a string of exactly n consecutive 5's.

A254500

a(n) is the smallest nonnegative integer such that a(n)! contains a string of exactly n consecutive 5's.

Terms

    a(0) =0a(1) =7a(2) =17a(3) =70a(4) =111a(5) =258a(6) =689a(7) =454a(8) =7133a(9) =15977a(10) =82869a(11) =111044a(12) =536687a(13) =384769a(14) =2750561a(15) =7063105

External references