A280591 - OEIS

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A280591

Fibbinary numbers n such that sigma(n) is also a Fibbinary number.

1, 10, 17, 20, 21, 41, 65, 66, 73, 132, 133, 137, 138, 148, 165, 170, 257, 258, 265, 276, 322, 337, 338, 517, 521, 522, 529, 545, 546, 553, 577, 581, 585, 593, 641, 642, 644, 645, 658, 673, 676, 682, 1032, 1033, 1044, 1097, 1153, 1169, 1172, 1193, 1289, 1297, 1316, 1321, 1361, 1364, 1365

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OFFSET

1,2

LINKS

Robert Israel, Table of n, a(n) for n = 1..10000

EXAMPLE

Fibbinary number 21 is a term because sigma(21) = 32 is also a Fibbinary number.

MAPLE

fibbinary:= n -> Bits:-And(n, 2*n)=0:

select(t -> fibbinary(t) and fibbinary(numtheory:-sigma(t)), [seq(i, i=1..2000)]); # Robert Israel, Apr 02 2018

MATHEMATICA

FibbinaryQ[n_] := BitAnd[n, 2 n] == 0; Select[Range[2000] - 1,