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.

A067820 The start of a record-breaking run of consecutive integers with a number of prime factors (counted with multiplicity) equal to 5.

Original entry on oeis.org

32, 944, 15470, 57967, 632148, 14845324, 69921004, 888781058, 2674685524, 10077383364, 21117216104, 393370860205, 3157222675953, 5509463413255, 24819420480104, 361385490681003, 441826936079342
Offset: 1

Views

Author

Shyam Sunder Gupta, Feb 07 2002

Keywords

Comments

a(16) > 3*10^13. - Brian Trial, May 13 2017
All multiples of 32 greater than 32 are of form 2^5*m and have at least 6 factors. Thus this sequence will be limited to a run of at most 31 integers. - Brian Trial, May 13 2017
a(18) > 2 * 10^15. - Toshitaka Suzuki, Aug 31 2025

Examples

			a(3)=15470 because 15470 is the start of a record breaking run of 3 consecutive integers (15470 to 15472) each having 5 prime factors; i.e. bigomega(n)=A001222(n)=5 for n = 15470, ..., 15472.
		

Crossrefs

Subsequence of A014614.

Programs

  • Mathematica
    bigomega[n_] := Plus@@Last/@FactorInteger[n]; For[n=1; m=l=0, True, n++, If[bigomega[n]==5, l++, If[l>m, m=l; Print[n-l, " ", l]]; l=0]]
    Table[SequencePosition[PrimeOmega[Range[15*10^6]],PadRight[{},n,5],1][[All,1]],{n,6}]//Flatten (* The program generates the first six terms of the sequence. *) (* Harvey P. Dale, Sep 03 2022 *)

Extensions

Edited by Dean Hickerson, Jul 31 2002
More terms from Jens Kruse Andersen, Aug 23 2003
a(13)-a(14) from Donovan Johnson, Jan 31 2009
a(15) from Brian Trial, May 13 2017
a(16)-a(17) from Toshitaka Suzuki, Aug 31 2025