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 A298816 a(n) is the binary XOR of all n-bit squares, with a(2)=0 indicating that no 2-bit squares exist. 2
 1, 0, 4, 9, 9, 21, 12, 28, 449, 577, 357, 997, 6085, 14533, 12517, 15077, 121125, 152869, 400028, 1041052, 1290704, 2556368, 4913664, 11950592, 22421376, 63692672, 7674753, 78355329, 312723717, 656197893, 1089399836, 2723474460, 4196236289, 2416016385, 8186515468 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,3 COMMENTS XOR is the binary exclusive-or operator. LINKS EXAMPLE There are two squares whose binary representation is 5 bits long, namely 16 and 25. a(5) = 9 because 25 XOR 16 = 9. There are four squares whose binary representation is 7 bits long, namely 64, 81, 100 and 121. a(7) = (64 XOR 81 XOR 100 XOR 121) = 12. PROG (Python) i = n = x = L = 1 while L < 47:     i+=1     nextn = i*i     if (nextn ^ n) > n:  # if lengths of binary representations are different         print str(x)+', ',         x = 0         prevL = L         L = len(bin(nextn))-2         for j in range(prevL, L-1):  print '0, ',     n = nextn     x ^= n CROSSREFS Cf. A000290, A007088, A070939. Sequence in context: A014719 A139417 A329732 * A095873 A141801 A177083 Adjacent sequences:  A298813 A298814 A298815 * A298817 A298818 A298819 KEYWORD nonn,base AUTHOR Alex Ratushnyak, Jan 26 2018 STATUS approved

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Last modified May 6 09:45 EDT 2021. Contains 343580 sequences. (Running on oeis4.)