A294029 Values of bsigma(k) = bsigma(k+1), where bsigma is the sum of the bi-unitary divisors (A188999).

24, 40, 60, 720, 960, 1440, 2160, 2640, 2400, 3000, 4320, 4320, 4320, 5280, 7400, 11520, 11880, 12960, 14400, 20160, 30240, 26640, 34560, 25200, 34560, 49920, 51840, 60480, 63360, 60480, 65280, 62400, 61560, 115200, 93600, 114912, 100800, 120960, 120960

Offset

1,1

Comments

The sum of bi-unitary divisors of numbers n such that n and n+1 have the same sum (A293183).

The bi-unitary version of A053215.

Links

Amiram Eldar, Table of n, a(n) for n = 1..2148

Formula

a(n) = A188999(A293183(n)).

Example

24 is in the sequence since 24 = bsigma(14) = bsigma(15).

Mathematica

f[n_] := Select[Divisors[n], Function[d, CoprimeQ[d, n/d]]]; bsigma[m_] := DivisorSum[m, # &, Last@Intersection[f@#, f[m/#]] == 1 &]; a = {}; b1 = 0; For[k = 0, k < 10^6, k++; b2 = bsigma[k]; If[b1 == b2, a = AppendTo[a, b1]]; b1 = b2]; a (* after Michael De Vlieger at A188999 *)

Crossrefs

Cf. A053215, A290303, A188999, A293183.

Sequence in context: A039296 A043899 A269452 * A366675 A195562 A026040

Adjacent sequences: A294026 A294027 A294028 * A294030 A294031 A294032

Keyword

nonn

Author

Amiram Eldar, Oct 22 2017

Status

approved