This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A088512 #21 Dec 04 2016 19:20:44 %S A088512 0,0,0,1,0,1,1,3,0,1,1,3,1,3,3,7,0,1,1,3,1,3,3,7,1,3,3,7,3,7,7,15,0,1, %T A088512 1,3,1,3,3,7,1,3,3,7,3,7,7,15,1,3,3,7,3,7,7,15,3,7,7,15,7,15,15,31,0, %U A088512 1,1,3,1,3,3,7,1,3,3,7,3,7,7,15,1,3,3,7 %N A088512 Number of partitions of n into two parts whose xor-sum is n. %F A088512 a(0) = 0, a(n) = A001316(n-m)-1, where m is the highest power of 2 less than n. - _Emmanuele Villa_, Nov 19 2016 %F A088512 a(2*n) = a(n), a(2*n + 1) = 2*a(n) + 1. - _Michael Somos_, Dec 04 2016 %e A088512 G.f. = x^3 + x^5 + x^6 + 3*x^7 + x^9 + x^10 + 3*x^11 + x^12 + 3*x^13 + 3*x^14 + ... %e A088512 From _Emmanuele Villa_, Nov 19 2016: (Start) %e A088512 For n = 47, the highest power of 2 less than n is 32, so a(47) = A001316(47-32) - 1 = A001316(15) - 1 = 16 - 1 = 15. %e A088512 For n = 63, the highest power of 2 less than n is 32, so a(63) = A001316(63-32) - 1 = A001316(31) - 1 = 32 - 1 = 31. (End) %t A088512 Table[2^DigitCount[# - 2^(Floor@ Log2@ # - Boole@ IntegerQ@ Log2@ #) - 1 + Boole[# == 1]/2, 2, 1] - 1 &[n + 1], {n, 0, 72}] (* _Michael De Vlieger_, Nov 18 2016 *) %t A088512 a[ n_] := Which[ n < 3, 0, EvenQ[n], a @ Quotient[n, 2], True, a[ Quotient[n, 2]] 2 + 1]; (* _Michael Somos_, Dec 04 2016 *) %o A088512 (PARI) a(n) = sum(m=1, n\2, bitxor(m,n-m)==n); \\ _Michel Marcus_, Dec 03 2016 %o A088512 (PARI) {a(n) = if( n<3, 0, n%2, a(n\2)*2 + 1, a(n\2))}; /* _Michael Somos_, Dec 04 2016 */ %Y A088512 Cf. A050315. %K A088512 easy,nonn,base %O A088512 0,8 %A A088512 _Naohiro Nomoto_, Nov 14 2003