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 A003815 a(0) = 0, a(n) = a(n-1) XOR n. 6
 0, 1, 3, 0, 4, 1, 7, 0, 8, 1, 11, 0, 12, 1, 15, 0, 16, 1, 19, 0, 20, 1, 23, 0, 24, 1, 27, 0, 28, 1, 31, 0, 32, 1, 35, 0, 36, 1, 39, 0, 40, 1, 43, 0, 44, 1, 47, 0, 48, 1, 51, 0, 52, 1, 55, 0, 56, 1, 59, 0, 60, 1, 63, 0, 64, 1, 67, 0 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,3 COMMENTS a(n) = ABS(A077140(n)) for n>0. - Reinhard Zumkeller, Oct 09 2007 LINKS Vincenzo Librandi, Table of n, a(n) for n = 0..1000 FORMULA a(n) = n+(-1)^n*a(n-1). - Vladeta Jovovic, Mar 13 2003 a(0)=0, a(4n+1)=1, a(4n+2)=4n+3, a(4n+3)=0, a(4n+4)=4n+4, n>=0. a(n) = f(n,0) with f(n,x) = if n=0 then x else if x is even then f(n-1,x+n) else f(n-1,x-n). - Reinhard Zumkeller, Oct 09 2007 G.f.: x*(1+3*x-x^2+x^3)/((1-x^4)*(1-x^2)). - Vincenzo Librandi, Oct 12 2013 MAPLE (1+3*x-x^2+x^3)*x/(1-x^4)/(1-x^2); MATHEMATICA an = 0; Reap[ For[i = 0, i <= 100, i++, an = BitXor[an, i]; Sow[an]]][[2, 1]] (* Jean-François Alcover, Oct 11 2013, translated from Pari *) CoefficientList[Series[x (1 + 3 x - x^2 + x^3)/((1 - x^4) (1 - x^2)), {x, 0, 100}], x] (* Vincenzo Librandi, Oct 12 2013 *) PROG (PARI) print1(an=0); for( i=1, 100, print1(", ", an=bitxor(an, i))) \\ M. F. Hasler, Oct 20 2008 CROSSREFS Cf. A003816. Cf. A077140 ; A145768. [M. F. Hasler, Oct 20 2008] Sequence in context: A319974 A138376 A077140 * A131486 A127445 A081170 Adjacent sequences:  A003812 A003813 A003814 * A003816 A003817 A003818 KEYWORD nonn,base AUTHOR STATUS approved

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Last modified February 22 16:40 EST 2019. Contains 320399 sequences. (Running on oeis4.)