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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 *) Select[Range[800], CompositeQ[#]&&Length[Union[IntegerLength[ #, 2]&/@ FactorInteger[ #][[All, 1]]]]==1&] (* Harvey P. Dale, Oct 11 2021 *) 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 * A344030 A350706 A036310 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 June 8 03:07 EDT 2023. Contains 363157 sequences. (Running on oeis4.)