

A217556


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


4



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
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OFFSET

1,2


LINKS

Table of n, a(n) for n=1..69.
E. Angelini, Odd/even: integers and digits alternate, SeqFan mailing list, Oct 06 2012


PROG

(PARI) A217556(n, show=0, a=1, u)={for( i=2, n, u+=1<<a; show & print1(a", "); for(t=1, 9e9, bittest(u, t) & next; bittest(t+a, 0)  next; !bittest(a%10 + t\10^(#Str(t)1), 0) & (t+=10^(#Str(t)1)1) & next; a=t; break )); a} \\  M. F. Hasler, Oct 06 2012


CROSSREFS

A simplified variant of A217555.
See also A217559, A217560, where "parity" is replaced by "primality".
Sequence in context: A048410 A180083 A275775 * A249873 A102491 A111706
Adjacent sequences: A217553 A217554 A217555 * A217557 A217558 A217559


KEYWORD

nonn,base


AUTHOR

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


STATUS

approved



