A308540 a(n) is the least nonnegative number whose digits do not appear in order (not necessarily consecutively) in the concatenation of all previous terms.
0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 22, 33, 44, 55, 66, 77, 88, 99, 100, 332, 554, 776, 998, 1001, 3322, 5544, 7766, 9988, 33220, 33221, 55445, 77667, 99889, 332200, 332211, 776674, 776675, 3322008, 3322009, 7766741, 7766755, 33220088, 33220099, 77667411
Offset: 1
Examples
The first terms are necessarily the one-digit numbers: a(1) = 0, a(2) = 1, ..., a(10) = 9. The number 10 does not appear in "0123456789", hence a(11) = 10. The digits of every number from 11 to 21 appear in order in "012345678910", but this is not the case for the number 22, hence a(12) = 22.
Links
- Rémy Sigrist, C program for A308540
Programs
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C
See Links section.
Comments