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 1-3 of 3 results.

A121069 Conjectured sequence for jumping champions greater than 1 (most common prime gaps up to x, for some x).

Original entry on oeis.org

2, 4, 6, 30, 210, 2310, 30030, 510510, 9699690, 223092870, 6469693230, 200560490130, 7420738134810, 304250263527210, 13082761331670030, 614889782588491410, 32589158477190044730, 1922760350154212639070
Offset: 1

Views

Author

Lekraj Beedassy, Aug 10 2006

Keywords

Comments

If n > 2, then a(n) = product of n-1 consecutive distinct prime divisors. E.g. a(5)=210, the product of 4 consecutive and distinct prime divisors, 2,3,5,7. - Enoch Haga, Dec 08 2007
From Bill McEachen, Jul 10 2022: (Start)
Rather than have code merely generating the conjectured values, one can compare values of sequence terms at the same position n. Specifically, locate new maximums where (p,p+even) are both prime, where even=2,4,6,8,... and the datum set is taken with even=4. A new maximum implies a new jumping champion.
Doing this produces the terms 2,4,6,30,210,2310,30030,.... Looking at the plot of a(n) ratio for gap=2/gap=6, the value changes VERY slowly, and is 2.14 after 50 million terms (one can see the trend via Plot 2 of A001359 vs A023201 (3rd option seqA/seqB vs n). The ratio for gap=4/gap=2 ~ 1, implying they are equally frequent. (End)

Crossrefs

Programs

  • Mathematica
    2,4,Table[Product[Prime[k],{k,1,n-1}],{n,3,30}]
  • PARI
    print1("2, 4");t=2;forprime(p=3,97,print1(", ",t*=p)) \\ Charles R Greathouse IV, Jun 11 2011

Formula

Consists of 4 and the primorials (A002110).
a(1) = 2, a(2) = 4, a(3) = 6, a(n+1)/a(n) = Prime[n] for n>2.

Extensions

Corrected and extended by Alexander Adamchuk, Aug 11 2006
Definition corrected and clarified by Jonathan Sondow, Aug 16 2011

A087104 Greatest jumping champion for prime(n).

Original entry on oeis.org

1, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 4, 2, 4, 2, 4, 4, 4, 4, 4, 4, 2, 2, 2, 4, 4, 6, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 6, 6, 6, 6, 6, 6, 6, 6, 6, 2, 6, 6, 6, 6, 6, 6, 6, 6, 6, 4, 4, 4, 4, 4, 4, 4, 6, 6, 6
Offset: 2

Views

Author

Reinhard Zumkeller, Aug 10 2003

Keywords

Comments

A number is called a jumping champion for n, if it is the most frequently occurring difference between consecutive primes <= n;
there are occasionally several jumping champions: see A087102; A087103(n) is the smallest jumping champion for prime(n);
a(n)<=6 for small n, see Odlyzko et al. for primes>1.7*10^35.

Crossrefs

Programs

  • Mathematica
    d=Table[0, {100}]; p=2; Table[q=NextPrime[p]; d[[q-p]]++; p=q; Position[d, Max[d]][[-1,1]], {1000}]

A087102 Number of numbers occurring most frequently as difference between consecutive primes <= prime(n).

Original entry on oeis.org

1, 2, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 2, 1, 2, 1, 2, 2, 1, 1, 2, 2, 1, 1, 1, 2, 2, 3, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 2, 2, 1, 1, 1, 1, 1, 2, 2, 1, 2, 2, 1, 1, 1, 2, 3, 3, 3, 1, 1, 1, 1, 1, 1, 1, 2, 2, 1
Offset: 2

Views

Author

Reinhard Zumkeller, Aug 10 2003

Keywords

Comments

For small n: a(n)<=3; A087103(n) and A087104(n) give the smallest and greatest jumping champion(s) for prime(n).

Crossrefs

Programs

  • Mathematica
    d=Table[0, {100}]; p=2; Table[q=NextPrime[p]; d[[q-p]]++; p=q; Length[Position[d, Max[d]]], {1000}]
Showing 1-3 of 3 results.