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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
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 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

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

EXAMPLE

1 is a term since s(1) = s(2) = 1;

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

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

CROSSREFS

The unitary version of A206368.

Cf. A206369, A307037.

Sequence in context: A255205 A117047 A089720 * A174202 A139850 A233416

Adjacent sequences:  A333405 A333406 A333407 * A333410 A333411 A333412

KEYWORD

nonn

AUTHOR

Amiram Eldar, Mar 19 2020

STATUS

approved

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Last modified June 4 01:54 EDT 2020. Contains 334812 sequences. (Running on oeis4.)