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 A151783 #17 Nov 17 2022 05:27:01 %S A151783 1,1,4,1,4,4,16,1,4,4,16,4,16,16,64,1,4,4,16,4,16,16,64,4,16,16,64,16, %T A151783 64,64,256,1,4,4,16,4,16,16,64,4,16,16,64,16,64,64,256,4,16,16,64,16, %U A151783 64,64,256,16,64,64,256,64,256,256,1024,1,4,4,16,4,16,16,64,4,16,16,64,16,64 %N A151783 a(n) = 4^(wt(n) - 1) where wt(n) = A000120(n). %e A151783 From _Omar E. Pol_, Jul 21 2009: (Start) %e A151783 If written as a triangle: %e A151783 1; %e A151783 1,4; %e A151783 1,4,4,16; %e A151783 1,4,4,16,4,16,16,64; %e A151783 1,4,4,16,4,16,16,64,4,16,16,64,16,64,64,256; %e A151783 1,4,4,16,4,16,16,64,4,16,16,64,16,64,64,256,4,16,16,64,16,64,64,256,16,64,... %e A151783 (End) %o A151783 (Python 3.10+) %o A151783 def A151783(n): return 1<<(n.bit_count()-1<<1) # _Chai Wah Wu_, Nov 15 2022 %Y A151783 Cf. A000120, A048881, A048896, A147610, A151780. %Y A151783 Cf. A000302, A102376. [_Omar E. Pol_, Jul 21 2009] %Y A151783 A102376 is a very similar sequence. %K A151783 nonn %O A151783 1,3 %A A151783 _N. J. A. Sloane_, Jun 25 2009