A349868 - OEIS

A349868

Nobly abundant numbers (A349758) that are not abundant numbers (A005101).

315, 495, 525, 585, 675, 693, 735, 765, 819, 825, 850, 855, 884, 950, 975, 988, 1012, 1035, 1071, 1078, 1125, 1150, 1196, 1197, 1210, 1215, 1274, 1275, 1276, 1287, 1292, 1305, 1323, 1364, 1395, 1425, 1449, 1450, 1508, 1550, 1564, 1612, 1617, 1628, 1665, 1666

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OFFSET

1,1

COMMENTS

This sequence if infinite. For example, 45*p is a term if p is a prime > 5.

LINKS

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

EXAMPLE

315 is a term since it is not abundant, A000203(315) = 624 < 2*315 = 630, and both A000005(315) = 12 and A000203(315) = 624 are abundant numbers.

MATHEMATICA

abQ[n_] := DivisorSigma[1, n] > 2*n; nobAbQ[n_] := And @@ abQ /@ DivisorSigma[{0, 1}, n]; Select[Range[2000], !abQ[#] && nobAbQ[#] &]

CROSSREFS