A085955 Composites such that the number of 1's in their binary expansion is equal to the number of 1's in the binary expansion of the sum of their prime factors (counting repetition).

4, 6, 9, 16, 20, 22, 24, 28, 36, 38, 49, 56, 65, 69, 70, 72, 84, 86, 92, 100, 104, 105, 118, 130, 132, 133, 134, 138, 148, 150, 152, 153, 162, 166, 176, 180, 184, 208, 209, 212, 214, 216, 256, 258, 259, 261, 262, 264, 266, 267, 278, 284, 320, 325, 326, 329, 345

Offset

1,1

Links

Amiram Eldar, Table of n, a(n) for n = 1..10000

Example

a(42) = 216 because 216 = '11011000' and sopfr(216) = 15 = '1111'; both have four 1's.

Mathematica

binWt[n_] := DigitCount[n, 2, 1]; seqQ[n_] := CompositeQ[n] && binWt[n] == binWt[Plus @@ Times @@@ FactorInteger[n]]; Select[Range[350], seqQ] (* Amiram Eldar, Dec 14 2019 *)

Crossrefs

Cf. A000120, A001414, A002808, A064548.

Sequence in context: A300131 A045114 A010436 * A266346 A181018 A155569

Adjacent sequences: A085952 A085953 A085954 * A085956 A085957 A085958

Keyword

easy,nonn,base

Author

Jason Earls, Aug 17 2003

Status

approved