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

 Please make a donation to keep the OEIS running. We are now in our 56th year. In the past year we added 10000 new sequences and reached almost 9000 citations (which often say "discovered thanks to the OEIS"). Other ways to donate

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A279645 a(n) = not (n XOR (n shift 1)). 3
 0, 0, 0, 1, 1, 0, 2, 3, 3, 2, 0, 1, 5, 4, 6, 7, 7, 6, 4, 5, 1, 0, 2, 3, 11, 10, 8, 9, 13, 12, 14, 15, 15, 14, 12, 13, 9, 8, 10, 11, 3, 2, 0, 1, 5, 4, 6, 7, 23, 22, 20, 21, 17, 16, 18, 19, 27, 26, 24, 25, 29, 28, 30, 31, 31, 30, 28, 29, 25, 24, 26, 27, 19, 18, 16 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,7 COMMENTS Values of n for which A279645(n) = 0 are given by A000975(k). Values of n for which A279645(n) = 1 are given by A097072(k) (for  k>1). LINKS Paolo P. Lava, Table of n, a(n) for n = 0..10000 Paolo P. Lava, First occurrence of n in A279645, for n <= 1000 Paolo P. Lava, Graph of the first 10000 terms Paolo P. Lava, Graph of the first occurrence of n in A279645, for n <= 1000 EXAMPLE 5044 converted to base 2 is 1001110110100. Then consider each pair of adjacent bits starting from MSD: if they are equal, 00 or 11, set 1 otherwise 0: (1+0) -> 0 (0+0) -> 1 (0+1) -> 0 (1+1) -> 1 (1+1) -> 1 (1+0) -> 0 (0+1) -> 0 (1+1) -> 1 (1+0) -> 0 (0+1) -> 0 (1+0) -> 0 (0+0) -> 1 We get 10110010001, so a(5044) = 1425. MAPLE P:=proc(n) local a, b, k; a:=0; b:=convert(n, base, 2); for k to nops(b)-1 do a:=a+((((b[k]+b[k+1]) mod 2)+1) mod 2)*2^(k-1); od; RETURN(a); end; [seq(P(i), i=0..100)]; # alternative ( R. J. Mathar, Jun 22 2020) A279645 := proc(n)     local dgs, L ;     dgs := convert(n, base, 2) ;     L := [] ;     for i from 2 to nops(dgs) do         if op(i, dgs) = op(i-1, dgs) then             L := [op(L), 1] ;         else             L := [op(L), 0] ;         fi ;     end do:     add( op(i, L)*2^(i-1), i=1..nops(L)) ; end proc: CROSSREFS Cf. A000975, A038554, A097072. Sequence in context: A131012 A083057 A099028 * A198197 A203400 A077869 Adjacent sequences:  A279642 A279643 A279644 * A279646 A279647 A279648 KEYWORD nonn,easy,look AUTHOR Paolo P. Lava, Dec 16 2016 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 December 2 19:12 EST 2020. Contains 338891 sequences. (Running on oeis4.)