|
%I #9 Aug 02 2015 16:51:33
%S 1,3,7,15,21,31,45,63,73,93,107,127,153,189,219,255,273,313,341,381,
%T 403,443,471,511,561,633,693,765,819,891,951,1023,1057,1137,1193,1273,
%U 1317,1397,1453,1533,1571,1651,1707,1787,1831,1911,1967,2047,2145,2289,2409
%N Positive integers that, when written in binary, are palindromes with a middle run of 1's.
%C All powers of two minus one are members. - _Robert G. Wilson v_, Jun 27 2010
%t fQ[n_] := Block[{id = IntegerDigits[n, 2]}, id == Reverse@ id && id[[ Ceiling[ Floor[ Log[2, n] + 1]/2] ]] == 1]; Select[ Range@ 2552, fQ@# &] (* _Robert G. Wilson v_, Jun 27 2010 *)
%Y Cf. A006995, A175543.
%K base,nonn
%O 1,2
%A _Leroy Quet_, Jun 23 2010
%E a(10)-a(51) from _Robert G. Wilson v_, Jun 27 2010
|
