cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

A358484 Numbers k such that k, k+1 and k+2 are all bi-unitary abundant numbers (A292982).

Original entry on oeis.org

268005374, 600350750, 2666847104, 2683146464, 2695309694, 2849458688, 3904592768, 4112553248, 5368737374, 6554410784, 6955574624, 8207456894, 8967010688, 9220179968, 9868366430, 10529171288, 12147283070, 12411630944, 12491149670, 13911605630, 14126720894, 14396391008
Offset: 1

Views

Author

Amiram Eldar, Nov 18 2022

Keywords

Examples

			268005374 is in the sequence since 268005374, 268005375 and 268005376 are all bi-unitary abundant numbers (A292982): bsigma(268005374) = 568995840 > 2 * 268005374, bsigma(268005375) = 540633600 > 2 * 268005375, and bsigma(268005376) = 541258200 > 2 * 268005376 (bsigma is the sum of bi-unitary divisors, A188999).
		

Crossrefs

Subsequence of A096536, A292982 and A318167.
Cf. A188999.

Programs

  • Mathematica
    f[p_, e_] := (p^(e + 1) - 1)/(p - 1) - If[OddQ[e], 0, p^(e/2)]; bsigma[1] = 1; bsigma[n_] := Times @@ f @@@ FactorInteger[n]; abQ[n_] := bsigma[n] > 2*n; v = Cases[Import["https://oeis.org/A096536/b096536.txt", "Table"], {, }][[;; , 2]]; Select[v, And @@ abQ /@ (# + {0, 1, 2}) &]