A328736 Numbers k such that at least one of sopfr(k-1) and sopfr(k+1) is greater than or equal to 2*sopfr(k).

16, 18, 20, 24, 28, 30, 32, 36, 40, 42, 44, 45, 48, 52, 54, 60, 63, 66, 68, 70, 72, 75, 78, 80, 81, 84, 85, 88, 90, 95, 96, 98, 100, 102, 104, 105, 108, 110, 112, 114, 117, 119, 121, 125, 126, 128, 130, 132, 133, 135, 136, 138, 140, 143, 144, 145

Offset

1,1

Comments

k-1 or k+1 or both have sums of prime factors at least twice the sum of prime factors of k.

Links

Table of n, a(n) for n=1..56.

Mathematica

sop[n_] := If[n<2, 0, Total[Times @@@ FactorInteger@ n]]; Select[ Range[2, 150], (s = 2 sop[#]; sop[#+1] >= s || sop[#-1] >= s) &] (* Giovanni Resta, Oct 27 2019 *)

Crossrefs

Cf. A001414, A328737, A328738.

Sequence in context: A077914 A273543 A274127 * A348143 A161874 A095953

Adjacent sequences: A328733 A328734 A328735 * A328737 A328738 A328739

Keyword

nonn

Author

Robert Bilinski, Oct 26 2019

Status

approved