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 A160700 a(n) = if n<16 then n else a(floor(n/16)) XOR (n mod 16). 21
 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 1, 0, 3, 2, 5, 4, 7, 6, 9, 8, 11, 10, 13, 12, 15, 14, 2, 3, 0, 1, 6, 7, 4, 5, 10, 11, 8, 9, 14, 15, 12, 13, 3, 2, 1, 0, 7, 6, 5, 4, 11, 10, 9, 8, 15, 14, 13, 12, 4, 5, 6, 7, 0, 1, 2, 3, 12, 13, 14, 15, 8, 9, 10, 11, 5, 4, 7, 6, 1, 0, 3, 2, 13 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,3 COMMENTS A very simple hash function for the nonnegative integers. a(A000079(n))=A133145(n); a(A000302(n))=A010685(n); a(A001025(n))=A161452(n); a(A161440(n))=0; a(A161441(n))=1; a(A161442(n))=2; a(A161443(n))=3; a(A161444(n))=4; a(A161445(n))=5; a(A161446(n))=6; a(A161447(n))=7; a(A161448(n))=8; a(A161449(n))=9; a(A161450(n))=10; a(A161451(n))=11; a(A161452(n))=12; a(A161453(n))=13; a(A161454(n))=14; a(A161455(n))=15. - Reinhard Zumkeller, Jun 10 2009 LINKS R. Zumkeller, Table of n, a(n) for n = 0..10000 MAPLE read("transforms") ; A160700 := proc(n)     if n < 16 then         n;     else         XORnos(procname(floor(n/16)), modp(n, 16))     end if; end proc: # R. J. Mathar, Jul 12 2016 MATHEMATICA a[n_] := a[n] = If[n < 16, n, a[Floor[n/16]] ~BitXor~ Mod[n, 16]]; Table[a[n], {n, 0, 100}] (* Jean-François Alcover, Jan 25 2018 *) PROG (Maxima) load(functs)\$ A160700(n):=if n<16 then n else logxor(floor(n/16), mod(n, 16))\$ makelist(A160700(n), n, 0, 60); /* Martin Ettl, Nov 05 2012 */ (Haskell) import Data.Bits (xor) a160700 n = a160700_list !! n a160700_list = [0..15] ++ map f [16..] where    f x = a160700 x' `xor` m :: Int where (x', m) = divMod x 16 -- Reinhard Zumkeller, Nov 07 2012 (PARI) a(n)=my(t=n%16); while(n>15, n>>=4; t=bitxor(t, n%16)); t \\ Charles R Greathouse IV, Jan 25 2018 CROSSREFS Sequence in context: A262437 A130909 A275993 * A002377 A053836 A025483 Adjacent sequences:  A160697 A160698 A160699 * A160701 A160702 A160703 KEYWORD nonn,easy AUTHOR Reinhard Zumkeller, Jun 01 2009 STATUS approved

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Last modified April 22 22:19 EDT 2021. Contains 343197 sequences. (Running on oeis4.)