A175544 Positive integers that, when written in binary, are palindromes with a middle run of 1's.

1, 3, 7, 15, 21, 31, 45, 63, 73, 93, 107, 127, 153, 189, 219, 255, 273, 313, 341, 381, 403, 443, 471, 511, 561, 633, 693, 765, 819, 891, 951, 1023, 1057, 1137, 1193, 1273, 1317, 1397, 1453, 1533, 1571, 1651, 1707, 1787, 1831, 1911, 1967, 2047, 2145, 2289, 2409

Offset

1,2

Comments

All powers of two minus one are members. - Robert G. Wilson v, Jun 27 2010

Links

Table of n, a(n) for n=1..51.

Mathematica

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 *)

Crossrefs

Cf. A006995, A175543.

Sequence in context: A043725 A182247 A121712 * A139208 A324727 A320026

Adjacent sequences: A175541 A175542 A175543 * A175545 A175546 A175547

Keyword

base,nonn

Author

Leroy Quet, Jun 23 2010

Extensions

a(10)-a(51) from Robert G. Wilson v, Jun 27 2010

Status

approved