A378553 The number of n-digit composite numbers with all digits distinct.

4, 61, 551, 4026, 24687, 125841, 510370, 1542450, 3120693, 3265920

Offset

1,1

Comments

This sequence is finite since there are no numbers at all which have 11 or more distinct decimal digits.

For n=10, the sum of 10 distinct digits is 0+1+..+9 = 45 which by "casting out 9s" shows such a number is divisible by 9 and so always composite.

Links

Table of n, a(n) for n=1..10.

Formula

a(n) <= A073531(n) with equality only for n = 10.

Example

a(2) = 61 because there are 61 two-digit composite numbers with distinct digits: 10, 12, 14, 15, 16, 18, 20, 21, 24, 25, 26, 27, 28, 30, 32, 34, 35, 36, 38, 39, 40, 42, 45, 46, 48, 49, 50, 51, 52, 54, 56, 57, 58, 60, 62, 63, 64, 65, 68, 69, 70, 72, 74, 75, 76, 78, 80, 81, 82, 84, 85, 86, 87, 90, 91, 92, 93, 94, 95, 96, 98.

Crossrefs

Cf. A073531, A210441, A073532.

Sequence in context: A131014 A118005 A132064 * A229666 A252973 A262654

Adjacent sequences: A378550 A378551 A378552 * A378554 A378555 A378560

Keyword

nonn,base,fini,full,new

Author

Shyam Sunder Gupta, Nov 30 2024

Status

approved