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

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

Intersection of A263837 and A349758.

Cf. A000005, A000203, A005101, A349869.

Sequence in context: A323380 A256575 A295990 * A349937 A076773 A114807

Adjacent sequences: A349865 A349866 A349867 * A349869 A349870 A349871

Keyword

nonn

Author

Amiram Eldar, Dec 03 2021

Status

approved