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.

A059865 Product_{i=4..n} (prime(i) - 6).

Original entry on oeis.org

1, 1, 1, 1, 5, 35, 385, 5005, 85085, 1956955, 48923875, 1516640125, 53082404375, 1964048961875, 80526007436875, 3784722349533125, 200590284525255625, 11032465648889059375, 672980404582232621875, 43743726297845120421875
Offset: 1

Views

Author

Labos Elemer, Feb 28 2001

Keywords

Comments

Arises in Hardy-Littlewood prime k-tuplet conjectural formulas. Also the sequence gives the exact numbers of X42424Y difference-pattern in dRRS[m], where m=modulus=A002110(n). See A049296 (=dRRS[210]=list of first differences of reduced residue system modulo 210=4th primorial). A pattern X42424Y corresponds to a residue-sextuple or it is their difference-quintuple, X,Y > 4. Analogous pattern for primes is in A022008.
a(352) has 1001 decimal digits. - Michael De Vlieger, Mar 06 2017

Examples

			a(7) = (prime(4)-6) * (prime(5)-6) * (prime(6)-6) * (prime(7)-6) = 1 * 5* 7 *11 = 385
 Also in one period of dRRS with 2,6,30,210,2310,... modulus [A002110(n)] 1,2,8,48,480,... differences occur [A005867(n)]. The number of X42424Y residue-difference-patterns are 0,1,1,1,5,... respectively starting at suitable residues coprime to A002110(n).
		

References

  • See A059862 for references.
  • Steven R. Finch, Mathematical Constants, Cambridge, 2003, pp. 84-94.

Crossrefs

Programs

  • Mathematica
    Table[Product[Prime@ i - 6, {i, 4, n}], {n, 19}] (* Michael De Vlieger, Mar 06 2017 *)
  • PARI
    a(n) = prod(k=4, n, prime(k) - 6); \\ Michel Marcus, Mar 06 2017

A059863 a(n) = Product_{i=3..n} (prime(i)-4).

Original entry on oeis.org

1, 1, 1, 3, 21, 189, 2457, 36855, 700245, 17506125, 472665375, 15597957375, 577124422875, 22507852492125, 967837657161375, 47424045200907375, 2608322486049905625, 148674381704844620625, 9366486047405211099375, 627554565176149143658125, 43301264997154290912410625
Offset: 1

Views

Author

Labos Elemer, Feb 28 2001

Keywords

References

  • See A059862 for references.
  • Steven R. Finch, Mathematical Constants, Cambridge, 2003, pp. 84-94.

Crossrefs

Programs

  • PARI
    a(n) = prod(i=3, n, prime(i)-4); \\ Michel Marcus, Aug 25 2019

Extensions

More terms from Michel Marcus, Aug 25 2019

A059864 a(n) = Product_{i=4..n} (prime(i)-5), where prime(i) is i-th prime.

Original entry on oeis.org

1, 1, 1, 2, 12, 96, 1152, 16128, 290304, 6967296, 181149696, 5796790272, 208684449792, 7930009092096, 333060381868032, 15986898329665536, 863292509801938944, 48344380548908580864, 2997351594032332013568
Offset: 1

Views

Author

Labos Elemer, Feb 28 2001

Keywords

Comments

Such products arise in Hardy-Littlewood prime k-tuplet conjectural formulas.

References

  • Steven R. Finch, Mathematical Constants, Cambridge, 2003, pp. 84-94.
  • R. K. Guy, Unsolved Problems in Number Theory, A8, A1
  • G. H. Hardy and E. M. Wright, An Introduction to the Theory of Numbers, 5th ed., Oxford Univ. Press, 1979.
  • G. Polya, Mathematics and Plausible Reasoning, Vol. II, Appendix Princeton UP, 1954

Crossrefs

Programs

  • Magma
    [n le 3 select 1 else (&*[NthPrime(j) -5: j in [4..n]]): n in [1..30]]; // G. C. Greubel, Feb 02 2023
    
  • Mathematica
    Join[{1,1,1},FoldList[Times,Prime[Range[4,20]]-5]] (* Harvey P. Dale, Dec 29 2018 *)
  • PARI
    a(n) = prod(k=4, n, prime(k)-5); \\ Michel Marcus, Dec 12 2017
    
  • SageMath
    def A059864(n): return product(nth_prime(j) -5 for j in range(4,n+1))
    [A059864(n) for n in range(1,31)] # G. C. Greubel, Feb 02 2023
Showing 1-3 of 3 results.