The OEIS is supported by the many generous donors to the OEIS Foundation.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A305425 a(n) = n/2 for even n, a(n) = A305422(n) for odd n. 4
 1, 1, 2, 2, 4, 3, 3, 4, 6, 5, 7, 6, 11, 7, 8, 8, 16, 9, 13, 10, 5, 11, 22, 12, 19, 13, 12, 14, 14, 15, 25, 16, 50, 17, 29, 18, 31, 19, 28, 20, 37, 21, 38, 22, 24, 23, 41, 24, 9, 25, 32, 26, 26, 27, 47, 28, 44, 29, 55, 30, 59, 31, 10, 32, 20, 33, 61, 34, 21, 35, 118, 36, 67, 37, 88, 38, 110, 39, 53, 40, 69, 41, 18, 42, 64, 43, 73, 44, 94, 45, 87, 46, 43, 47 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,3 COMMENTS Each k occurs exactly twice, at 2k and at A305421(k). LINKS Antti Karttunen, Table of n, a(n) for n = 1..65537 Index entries for sequences related to polynomials in ring GF(2)[X] FORMULA a(n) = n/2 if n is even, a(n) = A305422(n) if n is odd. PROG (PARI) A091225(n) = polisirreducible(Pol(binary(n))*Mod(1, 2)); A305419(n) = if(n<3, 1, my(k=n-1); while(k>1 && !A091225(k), k--); (k)); A305422(n) = { my(f = subst(lift(factor(Pol(binary(n))*Mod(1, 2))), x, 2)); for(i=1, #f~, f[i, 1] = Pol(binary(A305419(f[i, 1])))); fromdigits(Vec(factorback(f))%2, 2); }; A305425(n) = if(n%2, A305422(n), n/2); CROSSREFS Bisections: A000027 and A305422. Cf. also A252463. Sequence in context: A292421 A205563 A147594 * A212652 A303691 A205678 Adjacent sequences: A305422 A305423 A305424 * A305426 A305427 A305428 KEYWORD nonn AUTHOR Antti Karttunen, Jun 08 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 | Recents
The OEIS Community | Maintained by The OEIS Foundation Inc.

Last modified June 24 02:53 EDT 2024. Contains 373661 sequences. (Running on oeis4.)