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

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A305417 Permutation of natural numbers: a(0) = 1, a(2n) = A305421(a(n)), a(2n+1) = 2*a(n). 4
 1, 2, 3, 4, 7, 6, 5, 8, 11, 14, 9, 12, 21, 10, 15, 16, 13, 22, 29, 28, 49, 18, 27, 24, 69, 42, 63, 20, 107, 30, 17, 32, 19, 26, 23, 44, 35, 58, 39, 56, 127, 98, 83, 36, 151, 54, 45, 48, 81, 138, 207, 84, 475, 126, 65, 40, 743, 214, 189, 60, 273, 34, 51, 64, 25, 38, 53, 52, 121, 46, 57, 88, 173, 70, 101, 116, 233, 78, 105, 112, 199, 254, 129 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,2 COMMENTS This is GF(2)[X] analog of A005940, but note the indexing: here the domain starts from 0, although the range excludes zero. This sequence can be represented as a binary tree. Each child to the left is obtained by applying A305421 to the parent, and each child to the right is obtained by doubling the parent:                                      1                                      |                   ...................2...................                  3                                       4        7......../ \........6                   5......../ \........8       / \                 / \                 / \                 / \      /   \               /   \               /   \               /   \     /     \             /     \             /     \             /     \   11       14          9       12         21       10         15       16 13  22   29  28      49 18   27  24     69  42   63  20    107  30   17  32 Sequence A305427 is obtained by scanning the same tree level by level from right to left. LINKS Antti Karttunen, Table of n, a(n) for n = 0..16383 FORMULA a(0) = 1, a(2n) = A305421(a(n)), a(2n+1) = 2*a(n). a(n) = A305427(A054429(n)). For all n >= 1, a(A000079(n-1)) = A014580(n). PROG (PARI) A091225(n) = polisirreducible(Pol(binary(n))*Mod(1, 2)); A305420(n) = { my(k=1+n); while(!A091225(k), k++); (k); }; A305421(n) = { my(f = subst(lift(factor(Pol(binary(n))*Mod(1, 2))), x, 2)); for(i=1, #f~, f[i, 1] = Pol(binary(A305420(f[i, 1])))); fromdigits(Vec(factorback(f))%2, 2); }; A305417(n) = if(0==n, (1+n), if(!(n%2), A305421(A305417(n/2)), 2*(A305417((n-1)/2)))); CROSSREFS Cf. A305418 (inverse), A305427 (mirror image). Cf. A014580 (left edge from 2 onward), A305421. Cf. also A005940, A052330, A091202. Sequence in context: A085162 A182178 A326316 * A231550 A106453 A122199 Adjacent sequences:  A305414 A305415 A305416 * A305418 A305419 A305420 KEYWORD nonn,tabf AUTHOR Antti Karttunen, Jun 10 2018 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.

Last modified June 12 10:58 EDT 2021. Contains 344947 sequences. (Running on oeis4.)