A217556 Terms as well as ending/starting digits are of alternating parity; this is the lexicographically earliest injective sequence with this property.

1, 2, 3, 4, 5, 6, 7, 8, 9, 20, 11, 22, 13, 24, 15, 26, 17, 28, 19, 40, 31, 42, 33, 44, 35, 46, 37, 48, 39, 60, 51, 62, 53, 64, 55, 66, 57, 68, 59, 80, 71, 82, 73, 84, 75, 86, 77, 88, 79, 200, 91, 202, 93, 204, 95, 206, 97, 208, 99, 210, 101, 212, 103, 214, 105, 216, 107, 218, 109

Offset: 1

Author

Eric Angelini and M. F. Hasler, Oct 06 2012

Keywords

• nonn
• base

Links

• E. Angelini, Odd/even: integers and digits alternate, SeqFan mailing list, Oct 06 2012

Crossrefs

A simplified variant of A217555.

See also A217559, A217560, where "parity" is replaced by "primality".

Programs

PARI

A217556(n,show=0,a=1,u)={for( i=2, n, u+=1<M. F. Hasler, Oct 06 2012