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A175544 Positive integers that, when written in binary, are palindromes with a middle run of 1's. 1
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 (list; graph; refs; listen; history; text; internal format)
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

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Last modified June 5 18:48 EDT 2020. Contains 334854 sequences. (Running on oeis4.)