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.

Showing 1-2 of 2 results.

A080805 Numbers n such that A072475(n) divides A071221(n).

Original entry on oeis.org

1, 4, 5, 6, 8, 19, 20, 21, 23, 27, 28, 35, 48, 50, 53, 59, 79, 83, 86, 91, 113, 127, 133, 143, 148, 153, 158, 164, 177, 180, 181, 186, 188, 189, 191, 193, 198, 207, 213, 219, 220, 225, 227, 233, 235, 237, 241, 254, 258, 260, 265, 274, 276, 277, 296, 297, 306
Offset: 1

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Author

Ralf Stephan, Mar 24 2003

Keywords

Programs

  • PARI
    k=3; for(n=1, 500, p=1; s=0; for(i=1, n, while(isprime(k), k=k+1); p=p*k; s=s+k; k=k+1); if(p%s==0, print1(n", ")))

A077145 a(n) = floor(product of next n primes / product of next n composite numbers).

Original entry on oeis.org

0, 0, 0, 3, 17, 106, 590, 3090, 21092, 127889, 734604, 6252468, 32854824, 279387963, 1909105118, 12319099520, 95059552565, 740652053314, 4888570540807, 40743793439712, 307640708818550, 2379664631112651, 17269477509704034, 165628134793721883
Offset: 1

Views

Author

Amarnath Murthy, Oct 30 2002

Keywords

Crossrefs

Formula

a(n) = floor(A007467(n)/A071221(n)). - Michel Marcus, May 08 2025

Extensions

a(7)-a(9) from Donald Sampson (marsquo(AT)hotmail.com), Dec 08 2003
More terms from Sean A. Irvine, May 07 2025
Showing 1-2 of 2 results.