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 A348906 #42 Jul 04 2025 12:36:27 %S A348906 0,1,4,16,64,169,225,256,676,900,1024,2209,2704,3600,4096,5625,7921, %T A348906 8836,10201,10816,12321,13689,14400,16384,19321,20449,22201,22500, %U A348906 23409,26569,27889,28561,29929,30625,31684,32041,35344,38809,40401,40804,43264,49284,52441 %N A348906 Squares with a square number of 1's in their binary expansion. %C A348906 If a number k is of the form 2^(2*r), r >= 0, then k is included in this sequence. %H A348906 Amiram Eldar, <a href="/A348906/b348906.txt">Table of n, a(n) for n = 1..10000</a> %e A348906 225 is in the sequence because it is a square and the number of 1's in the binary expansion of 225 is 4 which is a square. %p A348906 q:= n-> issqr(add(i, i=Bits[Split](n))): %p A348906 select(q, [i^2$i=0..250])[]; # _Alois P. Heinz_, Nov 03 2021 %t A348906 Select[Range[0, 300]^2, IntegerQ @ Sqrt[DigitCount[#, 2, 1]] &] (* _Amiram Eldar_, Nov 03 2021 *) %o A348906 (PARI) isok(k) = issquare(k) && issquare(hammingweight(k)); \\ _Michel Marcus_, Nov 03 2021 %Y A348906 Intersection of A000290 and A084561. %Y A348906 Cf. A000120, A081092, A344603. %K A348906 nonn,base %O A348906 1,3 %A A348906 _Ctibor O. Zizka_, Nov 03 2021