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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
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
KEYWORD
nonn,easy
AUTHOR
Reinhard Zumkeller, Jun 01 2009
STATUS
approved

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Last modified July 22 06:32 EDT 2024. Contains 374481 sequences. (Running on oeis4.)