A333261 Numbers k such that A071324(k) = A071324(k+1).

1, 5, 51, 68, 87, 116, 171, 176, 591, 2108, 2403, 7143, 8787, 9308, 18548, 19371, 27387, 32127, 34887, 37928, 40131, 140667, 180548, 192428, 200996, 433311, 521727, 934449, 2476671, 2617563, 3960896, 8198156, 9670748, 11892512, 16585748, 19113651, 25367396, 25643012

Offset

1,2

Links

Amiram Eldar, Table of n, a(n) for n = 1..89 (terms below 10^10)

Example

1 is a term since A071324(1) = A071324(2) = 1.
5 is a term since A071324(5) = A071324(6) = 4.

Mathematica

f[n_] := Plus @@ (-(d = Divisors[n])*(-1)^(Range[Length[d], 1, -1])); seq = {}; f1 = f[1]; Do[f2 = f[n]; If[f1 == f2, AppendTo[seq, n-1]]; f1 = f2, {n, 2, 50000}]; seq
SequencePosition[Table[Total[Times@@@Partition[Riffle[Reverse[Divisors[n]], {1, -1}, {2, -1, 2}], 2]], {n, 2565*10^4}], {x_, x_}][[All, 1]] (* Harvey P. Dale, Nov 06 2022 *)

Crossrefs

Cf. A002961, A071324, A206368.

Sequence in context: A077681 A326738 A322927 * A117710 A064019 A134938

Adjacent sequences: A333258 A333259 A333260 * A333262 A333263 A333264

Keyword

nonn

Author

Amiram Eldar, Mar 13 2020

Status

approved