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A200878 Composite numbers whose prime factors have equal numbers of bits. 2
4, 6, 8, 9, 12, 16, 18, 24, 25, 27, 32, 35, 36, 48, 49, 54, 64, 72, 81, 96, 108, 121, 125, 128, 143, 144, 162, 169, 175, 192, 216, 243, 245, 256, 288, 289, 323, 324, 343, 361, 384, 391, 432, 437, 486, 493, 512, 527, 529, 551, 576, 589, 625, 648, 667, 713 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Arkadiusz Wesolowski, Table of n, a(n) for n = 1..10000

EXAMPLE

7429 = 17*19*23 -> 10001*10011*10111, therefore 7429 is a term.

7430 = 2*5*743 -> 10*101*1011100111, therefore 7430 is not a term.

MATHEMATICA

lst = {}; Do[b = IntegerDigits[FactorInteger[n], 2]; If[! PrimeQ[n] && Length[b[[-1, 1]]] == Length[b[[1, 1]]], AppendTo[lst, n]], {n, 4, 6!}]; lst (* Arkadiusz Wesolowski, Dec 03 2011 *)

PROG

(PARI) is(n)=my(f=factor(n)[, 1]); #binary(f[1])==#binary(f[#f])&&!isprime(n) \\ Charles R Greathouse IV, Dec 23 2011

CROSSREFS

Supersequence of A085721 and of A182302.

Sequence in context: A090419 A209799 A028958 * A036310 A046760 A115684

Adjacent sequences:  A200875 A200876 A200877 * A200879 A200880 A200881

KEYWORD

base,nonn

AUTHOR

Arkadiusz Wesolowski, Nov 23 2011

STATUS

approved

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Last modified March 18 13:47 EDT 2019. Contains 321289 sequences. (Running on oeis4.)