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.

A118750 a(n) = product[k=1..n] P(k), where P(k) is the largest prime <= 3*k. a(n) = product[k=1..n] A118749(k).

Original entry on oeis.org

3, 15, 105, 1155, 15015, 255255, 4849845, 111546435, 2565568005, 74401472145, 2306445636495, 71499814731345, 2645493145059765, 108465218947450365, 4664004414740365695, 219208207492797187665, 10302785752161467820255
Offset: 1

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Author

Jonathan Vos Post, Apr 29 2006

Keywords

Comments

Differs from (after first term) A048599 "Partial products of the sequence (A001097) of twin primes" after 8th term. Differs from (after first term) A070826 "One half of product of first n primes A000040" after 9th term. Analogous to A118455 a(1)=1. a(n) = product{k=1..n} P(k), where P(k) is the largest prime <= k.

Crossrefs

A118456 a(n) = Product_{k=1..n} P(k), where P(k) is the smallest prime >= k.

Original entry on oeis.org

2, 4, 12, 60, 300, 2100, 14700, 161700, 1778700, 19565700, 215222700, 2797895100, 36372636300, 618334817100, 10511691890700, 178698762141900, 3037878956412300, 57719700171833700, 1096674303264840300, 25223508975091326900, 580140706427100518700, 13343236247823311930100
Offset: 1

Views

Author

Leroy Quet, Apr 28 2006

Keywords

Examples

			a(5)=300 because the smallest primes that are not smaller than 1,2,3,4 and 5 are 2,2,3,5 and 5, respectively, having product 2*2*3*5*5=300.
		

Crossrefs

Programs

  • Maple
    a:=n->product(nextprime(k-1),k=1..n): seq(a(n),n=1..22); # Emeric Deutsch, Apr 29 2006
  • Mathematica
    FoldList[Times, Table[NextPrime[k - 1], {k, 22}]] (* Michael De Vlieger, Aug 21 2017 *)
  • PARI
    a(n) = prod(k=1, n, nextprime(k)); \\ Michel Marcus, Aug 20 2019

Extensions

More terms from Emeric Deutsch and Jonathan Vos Post, Apr 29 2006

A118747 a(n) = product[k=1..n] P(k), where P(k) is the largest prime <= 2*k. a(n) = product[k=1..n] A060308(k).

Original entry on oeis.org

2, 6, 30, 210, 1470, 16170, 210210, 2732730, 46456410, 882671790, 16770764010, 385727572230, 8871734161290, 204049885709670, 5917446685580430, 183440847252993330, 5686666264842793230, 176286654210126590130
Offset: 1

Views

Author

Jonathan Vos Post, Apr 29 2006

Keywords

Crossrefs

A118752 a(n) = product[k=0..n] P(k), where P(k) is the smallest prime > 3*n. a(n) = product[k=0..n] A118751(k).

Original entry on oeis.org

2, 10, 70, 770, 10010, 170170, 3233230, 74364290, 2156564410, 62540367890, 1938751404590, 71733801969830, 2654150672883710, 108820177588232110, 4679267636293980730, 219925578905817094310, 11656055682008305998430
Offset: 0

Views

Author

Jonathan Vos Post, Apr 29 2006

Keywords

Comments

Analogous to A118456 a(n) = product{k=1..n} P(k), where P(k) is the smallest prime >= k.

Crossrefs

Programs

  • Mathematica
    Rest[FoldList[Times,1,Table[NextPrime[3n],{n,0,20}]]] (* Harvey P. Dale, Mar 09 2014 *)

Extensions

Definition corrected by Harvey P. Dale, Mar 09 2014

A118748 a(n) = Product_{k=1..n} P(k), where P(k) is the smallest prime >= 2*k.

Original entry on oeis.org

2, 10, 70, 770, 8470, 110110, 1871870, 31821790, 604614010, 13906122230, 319840811290, 9275383527410, 268986122294890, 7800597546551810, 241818523943106110, 8947285385894926070, 331049559278112264590
Offset: 1

Views

Author

Jonathan Vos Post, Apr 29 2006

Keywords

Crossrefs

Showing 1-5 of 5 results.