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 A145830 #12 Feb 27 2017 02:00:58 %S A145830 1,7,9,16,47,63 %N A145830 Indices for which A145768 (XOR of squares of the numbers 1...n) is a power of 2. %C A145830 Next term is > 10^7. %C A145830 a(7) > 1.5*10^9. [_Jon E. Schoenfield_, Jan 14 2009] %C A145830 a(7) > 10^11. [_Sean A. Irvine_, Aug 12 2010] %t A145830 Position[ FoldList[ BitXor, 0, Range[10^6]^2], n_ /; IntegerQ[Log[2, n]]] - 1 // Flatten (* _Jean-François Alcover_, Sep 30 2013 *) %o A145830 (PARI) an=0; for( i=1,10^6, an=bitxor(an,i^2); an & an==1<<valuation(a,2) & print1(i",")) %Y A145830 A145830 = A145768 intersect A000079. A145768(a(n)) = 2^A145831(n); See also A145827-A145829. %K A145830 more,nice,nonn %O A145830 1,2 %A A145830 _M. F. Hasler_, Oct 20 2008