A397432 - OEIS

%I #7 Jul 07 2026 21:34:21

%S 35,39,69,75,87,95,111,133,135,141,147,155,159,171,175,183,187,207,

%T 215,259,261,265,267,279,285,287,291,299,301,303,309,315,319,327,333,

%U 335,339,343,351,363,371,375,391,399,411,423,447,519,525,527,529,531,5373

%N Composites in A161601 whose binary reversal is composite.

%t p[f_] := Module[{n = 1, c = 0}, Reap[While[c < f, With[{d = IntegerDigits[n, 2]}, With[{r = Reverse[d]}, If[d =!= r && n < FromDigits[r, 2],

%t Sow[{n, FromDigits[r, 2]}]; c++]]]; n += 2]][[2, 1]]];

%t u = Select[p[300], !PrimeQ[#[[1]]] && !PrimeQ[#[[2]]] &];

%t Map[First, u]

%t (* _Peter J. C. Moses_, Jun 24 2026 *)

%Y Cf. A000040, A002808, A161601, A161603, A397429, A397430, A397431.

%K nonn,base,easy,new

%O 1,1

%A _Clark Kimberling_, Jun 26 2026