A335251 -id:A335251 - cp's OEIS frontend

A335252 Numbers k such that k and k+2 have the same unitary abundance (A129468).

12, 63, 117, 323, 442, 1073, 1323, 1517, 3869, 5427, 6497, 12317, 18419, 35657, 69647, 79919, 126869, 133787, 151979, 154007, 163332, 181427, 184619, 333797, 404471, 439097, 485237, 581129, 621497, 825497, 1410119, 2696807, 3077909, 3751619, 5145341, 6220607

Offset: 1

Amiram Eldar, May 28 2020

nonn

Are 12, 442 and 163332 the only even terms?
Are there any unitary abundant numbers (A034683) in this sequence?
No further even terms up to 10^13. - Giovanni Resta, May 30 2020

			12 is a term since 12 and 14 have the same unitary abundance: A129468(12) = usigma(12) - 2*12 = 20 - 24 = -4, and A129468(14) = usigma(14) - 2*14 = 24 - 28 = -4.

Amiram Eldar, Table of n, a(n) for n = 1..300

The unitary version of A330901.

Cf. A034448, A034683, A129468, A129487, A335251.

usigma[1] = 1; usigma[n_] := Times @@ (1 + Power @@@ FactorInteger[n]); udef[n_] := 2*n - usigma[n]; Select[Range[10^5], udef[#] == udef[# + 2] &]

cp's OEIS Frontend

A335252 Numbers k such that k and k+2 have the same unitary abundance (A129468).

Views

Author

Keywords

Comments

Examples

Links

Crossrefs

Programs

Mathematica