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 1-5 of 5 results.

A294194 a(n) is the sum of primes between n!+1 and (n+1)!.

Original entry on oeis.org

0, 2, 8, 90, 1493, 40148, 1536501, 78716604, 5275720734, 445867194366, 46449459576595, 5844108759723625, 873766735145244948, 153087877536458860660, 31062245895591356844637, 7225340509057562100376047, 1909774727511978452561271489, 569166269815032401548622424344
Offset: 0

Views

Author

Olivier Gérard, Oct 22 2017

Keywords

Examples

			a(2) = 3 + 5 = 8.
a(3) = 7 + 11 + 13 + 17 + 19 + 23 = 90.
		

Crossrefs

Cf. A063959.
Cf. A007504 (sum of first n primes).
Cf. A061232 (number of primes between n!+1 and (n+1)!).
Cf. A294193 (sum of integers between n!+1 and (n+1)!).
Cf. A294195 (product of primes between n!+1 and (n+1)!).

Programs

Formula

a(n) = A063959(n+1) - A063959(n). - Amiram Eldar, Jun 14 2024

Extensions

a(11)-a(13) from Iain Fox, Nov 23 2017
a(14) from Iain Fox, Nov 28 2017
a(15)-a(17) from Daniel Suteu, Nov 15 2018

A294195 Product of all primes between n!+1 and (n+1)!.

Original entry on oeis.org

1, 2, 15, 7436429, 141690116050851861774628683971583952877
Offset: 0

Views

Author

Olivier Gérard, Oct 29 2017

Keywords

Comments

The next term has 251 digits in base 10.

Crossrefs

Cf. A061232 (number of primes between n!+1 and (n+1)!).
Cf. A294193 (sum of integers between n!+1 and (n+1)!).
Cf. A294194 (sum of primes between n!+1 and (n+1)!).
Cf. A294196 (log of product of primes between n!+1 and (n+1)!).

Programs

  • Mathematica
    Table[Times @@ Table[Prime[i], {i, PrimePi[n!] + 1, PrimePi[(n + 1)!]}], {n, 0, 4}]

A294196 Floor of log of product of all primes between n!+1 and (n+1)!.

Original entry on oeis.org

2, 15, 87, 579, 4276, 35103, 322168, 3264471, 36285842, 439070392, 5747983086
Offset: 2

Views

Author

Olivier Gérard, Oct 29 2017

Keywords

Examples

			a(3) = floor(log(7*11*13*17*19*23)) = floor(15.82) = 15.
		

Crossrefs

Cf. A061232 (number of primes between n!+1 and (n+1)!).
Cf. A294194 (sum of primes between n!+1 and (n+1)!).
Cf. A294195 (product of primes between n!+1 and (n+1)!).

Programs

  • Mathematica
    Table[Floor[Plus @@ Table[Log[Prime[i]*1.], {i, PrimePi[n!] + 1, PrimePi[(n + 1)!]}]], {n, 2, 11}]

Extensions

a(12) from Daniel Suteu, Nov 15 2018

A346425 a(n) is the greatest number k such that k! <= prime(n).

Original entry on oeis.org

2, 2, 2, 3, 3, 3, 3, 3, 3, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5
Offset: 1

Views

Author

Bernard Schott, Jul 16 2021

Keywords

Comments

Terms 2, 3, 4, 5, ... appear respectively 3, 6, 21, 98, ... times consecutively; indeed, 2 appears A061232(1) + A061232(2) times, then every m >= 3 appears A061232(m) times.

Examples

			prime(1) = 2 and the greatest k with k! <= 2 is 2, so a(1) = 2.
prime(4) = 7 and the greatest k with k! <= 7 is 3, so a(4) = 3.
prime(10) = 29 and the greatest k with k! <= 29 is 4 so a(10) = 4.
Rows with n, prime(n), greatest k! <=n, a(n) for n = 1..14
      n        1    2    3    4    5    6    7    8    9   10   11   12   13   14
   prime(n)    2    3    5    7   11   13   17   19   23   29   31   37   41   43
  greatest k!  2    2    2    6    6    6    6    6    6   24   24   24   24   24
    a(n)       2    2    2    3    3    3    3    3    3    4    4    4    4    4
		

Crossrefs

Programs

  • PARI
    a(n) = my(k=1); until (k! > prime(n), k++); k-1; \\ Michel Marcus, Jul 19 2021

Formula

a(n)! = A000040(n) - A136437(n).

A294197 Floor of log base n! of product of all primes between n!+1 and (n+1)!.

Original entry on oeis.org

3, 8, 27, 120, 650, 4117, 30380, 255000, 2402333, 25086428, 287582999
Offset: 2

Views

Author

Olivier Gérard, Oct 29 2017

Keywords

Examples

			a(3) = floor(log(7436429)/log(6)) = floor(8.830...) = 8.
		

Crossrefs

Cf. A061232 (number of primes between n!+1 and (n+1)!).
Cf. A294195 (product of primes between n!+1 and (n+1)!).
Cf. A294196 (log of product of primes between n!+1 and (n+1)!).

Programs

  • Mathematica
    Table[Floor[1/Log[n!] Plus @@ Table[Log[Prime[i]*1.], {i, PrimePi[n!] + 1, PrimePi[(n + 1)!]}]], {n, 2, 10}]
  • PARI
    a(n) = floor(log(vecprod(primes([n!+1, (n+1)!])))/log(n!)); \\ Michel Marcus, Jan 19 2025

Formula

a(n) = Sum_{i=primepi(n!)+1..primepi((n+1)!)} log(prime(i)) / log(n!).

Extensions

a(12) from Jinyuan Wang, Jan 19 2025
Showing 1-5 of 5 results.