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.

A354217 Primes p such that the squarefree kernel of the product of the composite numbers between p and the next prime after p (A076978) sets a new record.

Original entry on oeis.org

3, 5, 7, 13, 19, 23, 31, 47, 53, 73, 83, 89, 113, 199, 211, 293, 467, 523, 887, 1129, 1327, 2971, 3271, 4297, 4831, 5591, 8467, 9551, 12853, 14107, 15683, 19609, 25471, 31397, 89689, 107377, 134513, 155921, 265621, 338033, 360653, 370261, 492113, 1098847, 1349533
Offset: 1

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Author

Hugo Pfoertner, May 19 2022

Keywords

Crossrefs

Programs

  • Mathematica
    s = Array[Times @@ FactorInteger[Times @@ Range[#1 + 1, #2 - 1]][[All, 1]] & @@ Map[Prime, # + {0, 1}] &, 2^15]; Prime@ Map[FirstPosition[s, #][[1]] &, Union@ FoldList[Max, s]] (* Michael De Vlieger, May 20 2022 *)
  • PARI
    a354217(limit) = {my(mp=0,pp=3); forprime(p=5,limit,my(L=List()); for(j=pp+1,p-1, my(f=factor(j),nf=#f~); for(k=1,nf, listput(~L,f~[1,k]))); listsort(L,1); my(mpp=prod(k=1,#L,L[k])); if(mpp>mp,print1(pp,", ");mp=mpp); pp=p)};
    a354217(1500000)