A087745 - OEIS

%I #13 May 03 2023 09:13:34

%S 1,1,3,3,5,5,15,15,17,17,51,51,85,85,255,255,257,257,771,771,1285,

%T 1285,3855,3855,4369,4369,13107,13107,21845,21845,65535,65535,65537,

%U 65537,196611,196611,327685,327685,983055,983055,1114129,1114129

%N Numbers A001317 repeated.

%C Triangles A049444, A049459, A051338, A051379, A051523 (Mitrinovic's triangles) mod 2 converted to decimal.

%C Sequence [1, 3, 5, 15, 17, 51, 85, 255, 257, ...] = A001317.

%o (Python)

%o def A087745(n): return sum((bool(~(m:=n>>1)&m-k)^1)<<k for k in range((n>>1)+1)) # _Chai Wah Wu_, May 02 2023

%Y Cf. A001317, A049444, A049459, A051338, A051378, A051523.

%K easy,nonn

%O 0,3

%A _Philippe Deléham_, Oct 02 2003

%E Definition corrected and edited by _Omar E. Pol_, Dec 24 2008