A333408 Numbers k such that s(k) = s(k+1), where s(k) is the unitary analog of the alternating sum-of-divisors function (A307037).

1, 11, 71, 155, 194, 204, 1119, 1420, 1628, 3705, 5186, 14363, 19788, 20467, 25180, 25545, 25843, 28251, 30804, 42811, 60204, 63180, 71791, 73260, 83600, 87219, 87308, 91539, 97432, 99208, 100456, 100471, 119315, 122616, 132308, 135340, 135864, 164691, 166624

Offset: 1

Author

Amiram Eldar, Mar 19 2020

Keywords

• nonn

Examples

			1 is a term since s(1) = s(2) = 1;
11 is a term since s(11) = s(12) = 10;
		

Links

• Amiram Eldar, Table of n, a(n) for n = 1..1000

Crossrefs

The unitary version of A206368.

Cf. A206369, A307037.

Programs

Mathematica

f[p_, e_] := p^e + (-1)^e; s[1] = 1; s[n_] := Times @@ f @@@ FactorInteger[n]; seq = {}; s1 = 1;  Do[s2 = s[n]; If[s1 == s2, AppendTo[seq, n - 1]]; s1 = s2, {n, 2, 10^5}]; seq