Number of n-digit numbers m such that (a) the digits of m are from the set {1, 2, 3, 4, 5}, (b) any digit that appears in m appears at least twice.
A171726
Number of n-digit numbers m such that (a) the digits of m are from the set {1, 2, 3, 4, 5}, (b) any digit that appears in m appears at least twice.
Terms
- a(0) =0a(1) =5a(2) =5a(3) =65a(4) =205a(5) =1405a(6) =7425a(7) =44385a(8) =271205a(9) =1666925a(10) =10312945a(11) =63728065a(12) =389047365a(13) =2328509565a(14) =13621340225a(15) =77892637505a(16) =436228078405
External references
- oeis: A171726