login
The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A249494 Lexicographically earliest permutation of the positive integers such that the parity of the first digit of a(n+1) equals that of a(n)'s last digit. 1
1, 3, 5, 7, 9, 10, 2, 4, 6, 8, 20, 21, 11, 12, 22, 23, 13, 14, 24, 25, 15, 16, 26, 27, 17, 18, 28, 29, 19, 30, 40, 41, 31, 32, 42, 43, 33, 34, 44, 45, 35, 36, 46, 47, 37, 38, 48, 49, 39, 50, 60, 61, 51, 52, 62, 63, 53, 54, 64, 65, 55, 56, 66, 67, 57, 58, 68, 69, 59, 70, 80, 81, 71, 72, 82, 83, 73, 74, 84, 85, 75, 76, 86, 87, 77, 78, 88, 89, 79, 90, 200 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

See A249278 (and inverse A249279) for the variant based on nonnegative integers; A162501 is a variant based not on parity but on equality.

See A249506 for the inverse permutation.

LINKS

Table of n, a(n) for n=1..91.

Index entries for sequences that are permutations of the natural numbers

PROG

(PARI) a(n, a=1, u=0)=for(n=1, n, for(k=1, 9e9, !bittest(u, k)&&k\10^(#Str(k)-1)==Mod(a, 2)&&!print1(a=k", ")&&break); u+=1<<a); a

CROSSREFS

Cf. A000030, A162501, A249278, A249279, A249506.

Sequence in context: A218452 A007731 A306590 * A047747 A007957 A194377

Adjacent sequences:  A249491 A249492 A249493 * A249495 A249496 A249497

KEYWORD

nonn,base

AUTHOR

M. F. Hasler, Oct 30 2014

STATUS

approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified October 26 05:58 EDT 2021. Contains 348257 sequences. (Running on oeis4.)