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 1-10 of 10 results.

A098416 (A007529(n) + A098415(n)) / 4.

Original entry on oeis.org

4, 5, 7, 8, 10, 20, 22, 35, 50, 52, 53, 55, 97, 98, 113, 115, 140, 155, 157, 175, 230, 232, 308, 322, 412, 413, 428, 430, 440, 442, 545, 547, 640, 650, 652, 713, 715, 725, 742, 743, 745, 805, 833, 848, 893, 935, 937, 938, 998, 1000, 1042, 1043, 1070, 1120, 1135
Offset: 1

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Author

Reinhard Zumkeller, Sep 07 2004

Keywords

Comments

(A007529(n),2*a(n)+A098417(n), A098415(n)) is a prime triple (p,q,r) with p

A098417 A098414(n) - (A007529(n) + A098415(n))/2.

Original entry on oeis.org

-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, 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, 1, -1, -1, 1, -1, -1, -1, 1, 1, -1, -1, 1, -1, -1, -1, 1, -1, 1, 1, -1
Offset: 1

Author

Reinhard Zumkeller, Sep 07 2004

Keywords

Comments

(A007529(n),2*A098416(n)+a(n), A098415(n)) is a prime triple (p,q,r) with p

A007529 Prime triples: p; p+2 or p+4; p+6 all prime.

Original entry on oeis.org

5, 7, 11, 13, 17, 37, 41, 67, 97, 101, 103, 107, 191, 193, 223, 227, 277, 307, 311, 347, 457, 461, 613, 641, 821, 823, 853, 857, 877, 881, 1087, 1091, 1277, 1297, 1301, 1423, 1427, 1447, 1481, 1483, 1487, 1607, 1663, 1693, 1783, 1867, 1871, 1873, 1993, 1997
Offset: 1

Keywords

Comments

Or, prime(m) such that prime(m+2) = prime(m)+6. - Zak Seidov, May 07 2012

References

  • H. Riesel, "Prime numbers and computer methods for factorization", Progress in Mathematics, Vol. 57, Birkhauser, Boston, 1985, Chap. 4, see p. 65.
  • N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).

Crossrefs

Programs

  • Magma
    [NthPrime(n): n in [1..310] | (NthPrime(n)+6) eq NthPrime(n+2)]; // Bruno Berselli, May 07 2012
    
  • Maple
    N:= 10000: # to get all terms <= N
    Primes:= select(isprime, [seq(2*i+1, i=1..floor((N+5)/2))]):locs:= select(t -> Primes[t+2]-Primes[t]=6, [$1..nops(Primes)-2]):
    Primes[locs]; # Robert Israel, Apr 30 2015
  • Mathematica
    ptrsQ[n_]:=PrimeQ[n+6]&&(PrimeQ[n+2]||PrimeQ[n+4])
    Select[Prime[Range[400]],ptrsQ]  (* Harvey P. Dale, Mar 08 2011 *)
  • PARI
    p=2;q=3;forprime(r=5,1e4,if(r-p==6,print1(p", "));p=q;q=r) \\ Charles R Greathouse IV, May 07 2012

Formula

a(n) = A098415(n) - 6. - Zak Seidov, Apr 30 2015

A098412 Greatest members p of prime triples (p-6, p-4, p).

Original entry on oeis.org

11, 17, 23, 47, 107, 113, 197, 233, 317, 353, 467, 647, 827, 863, 887, 1097, 1283, 1307, 1433, 1487, 1493, 1613, 1877, 2003, 2087, 2243, 2273, 2663, 2693, 3257, 3467, 3533, 3677, 3923, 4007, 4133, 4523, 4643, 4793, 4937, 4973, 5237, 5483, 5507, 5657, 6203
Offset: 1

Author

Reinhard Zumkeller, Sep 07 2004

Keywords

Comments

Subsequence of A046117; a(n) = A073648(n) + 4 = A022004(n) + 6.

Crossrefs

Programs

  • Magma
    [p: p in PrimesUpTo(6500)|IsPrime(p) and IsPrime(p-6) and IsPrime(p-4)]; // Vincenzo Librandi, Dec 26 2010
  • Maple
    K:=10^7: # to get all terms <= K.
    for n from 1 by 2 to K do; if isprime(n-6) and isprime(n-4) and isprime(n) then print(n) else fi; od;  # Muniru A Asiru, Aug 06 2017
  • Mathematica
    Select[Table[Prime[n], {n, 1000}], PrimeQ[# - 4] && PrimeQ[# - 6] &] (* Vladimir Joseph Stephan Orlovsky, Jun 19 2011 *)
    Select[Partition[Prime[Range[1000]],3,1],Differences[#]=={2,4}&][[All,3]] (* Harvey P. Dale, Sep 23 2017 *)

A098413 Greatest members p of prime triples (p-6, p-2, p).

Original entry on oeis.org

13, 19, 43, 73, 103, 109, 199, 229, 283, 313, 463, 619, 829, 859, 883, 1093, 1303, 1429, 1453, 1489, 1669, 1699, 1789, 1873, 1879, 1999, 2089, 2143, 2383, 2689, 2713, 2803, 3169, 3259, 3463, 3469, 3853, 4159, 4519, 4789, 5233, 5419, 5443, 5653, 5659, 5743
Offset: 1

Author

Reinhard Zumkeller, Sep 07 2004

Keywords

Comments

Subsequence of A046117; a(n) = A073649(n) + 2 = A022005(n) + 6.

Crossrefs

Programs

  • Magma
    [p: p in PrimesUpTo(6500)|IsPrime(p) and IsPrime(p-6) and IsPrime(p-2)]; // Vincenzo Librandi, Dec 26 2010
  • Mathematica
    Transpose[Select[Partition[Prime[Range[800]],3,1],Differences[#] == {4,2}&]][[3]] (* Harvey P. Dale, Aug 21 2013 *)

A098420 Members of prime triples (p,q,r) with p < q < r = p + 6.

Original entry on oeis.org

5, 7, 11, 13, 17, 19, 23, 37, 41, 43, 47, 67, 71, 73, 97, 101, 103, 107, 109, 113, 191, 193, 197, 199, 223, 227, 229, 233, 277, 281, 283, 307, 311, 313, 317, 347, 349, 353, 457, 461, 463, 467, 613, 617, 619, 641, 643, 647, 821, 823, 827, 829, 853, 857, 859, 863
Offset: 1

Author

Reinhard Zumkeller, Sep 07 2004

Keywords

Comments

A098418(a(n)) > 0; complement of A098419 in A000040.
Union of A007529, A098414 and A098415.

Programs

  • Mathematica
    lst={};Do[p=Prime[n];If[PrimeQ[p2=p+2]&&PrimeQ[p6=p+6], AppendTo[lst, p];AppendTo[lst, p2];AppendTo[lst, p6]];If[PrimeQ[p4=p+4]&&PrimeQ[p6=p+6], AppendTo[lst, p];AppendTo[lst, p4];AppendTo[lst, p6]], {n, 6!}];Union[lst] (* Vladimir Joseph Stephan Orlovsky, Sep 25 2008 *)

A098418 Number of prime triples (p,q,r) with p

Original entry on oeis.org

0, 0, 1, 2, 3, 3, 3, 2, 1, 0, 0, 1, 2, 2, 1, 0, 0, 0, 1, 1, 1, 0, 0, 0, 1, 2, 3, 3, 2, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 2, 2, 1, 0, 1, 2, 2, 1, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1, 0, 1, 2, 2, 1, 0, 0, 1, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 2, 2, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0
Offset: 1

Author

Reinhard Zumkeller, Sep 07 2004

Keywords

Comments

0 <= a(n) <= 3;
a(A098419(n))=0; a(A098420(n))>0; a(A098421(n))=1; a(A098422(n))=2; a(A098423(n))=3.

Examples

			A000040(13)=41: A007529(7)=41, A098414(6)=41 and
A098415(k)<>41 for all k, therefore a(13)=2.
		

Crossrefs

A098424 Number of prime triples (p,q,r) <= n with p

Original entry on oeis.org

0, 0, 0, 0, 1, 1, 2, 2, 2, 2, 3, 3, 4, 4, 4, 4, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 6, 6, 6, 6, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 9, 9, 9, 9, 10, 10, 11
Offset: 1

Author

Reinhard Zumkeller, Sep 07 2004

Keywords

Comments

Convention: a prime triple is <= n iff its smallest member is <= n;
a(n) <= A098428(n).

Examples

			a(15) = #{(5,7,11),(7,11,13),(11,13,17),(13,17,19)} = 4.
		

Crossrefs

Programs

  • Haskell
    a098424 n = length [(p,q,r) | p <- takeWhile (<= n) a000040_list,
                let r = p + 6, a010051 r == 1, q <- [p+1..r-1], a010051 q == 1]
    -- Reinhard Zumkeller, Nov 15 2011
  • Mathematica
    With[{pts=Select[Partition[Prime[Range[1200]],3,1],Last[#]-First[#] == 6&]}, Table[Count[pts,?(First[#]<=n&)],{n,110}]] (* _Harvey P. Dale, Nov 09 2011 *)

A098423 Primes occurring in exactly three prime triples (p,q,r) with p

Original entry on oeis.org

11, 13, 17, 103, 107, 1487, 1873, 3463, 5653, 15733, 16063, 16067, 19423, 19427, 21017, 22277, 43783, 43787, 55337, 79693, 88813, 101113, 144167, 165707, 166847, 195737, 201827, 225347, 247607, 257863, 266683, 268817, 276043, 284743
Offset: 1

Author

Reinhard Zumkeller, Sep 07 2004

Keywords

Comments

A098418(a(n)) = 3; subsequence of A098420.
This sequence consists of all integers of the form (prime(m)*prime(m+4)+36)/prime(m+2), for m>0, where prime(m) = A000040(m). Also note that the integers resulting from that rule equal prime(m+2), therefore a(n) also consists of all integers of the form sqrt[prime(m)*prime(m+4)+36]. - Richard R. Forberg, Jan 11 2016

Examples

			A000040(27)=103: A007529(11)=103, A098414(10)=103 and A098415(9)=103, therefore 103 is a term.
		

Crossrefs

A055737 Number of prime triples < 10^n, where a prime triple means 3 successive primes of the form {p, p+2, p+4} or {p, p+4, p+6}.

Original entry on oeis.org

0, 8, 30, 112, 507, 2837, 17220, 111156, 759256, 5425573, 40174725, 305689269, 2379622234, 18887841658
Offset: 1

Author

Robert G. Wilson v, Jun 09 2000

Keywords

Comments

For this sequence all three members of the triple must be below the 10^n bound. - Sean A. Irvine, Apr 04 2022

References

  • J. Recreational Math., vol. 23, No. 2, 1991, p. 97.

Crossrefs

Programs

  • Mathematica
    x=168; a=Table[ Prime[ n ], {n, 1, x} ] c=0; Do[ If[ a[[ n ]]+6==a[ [ n+2 ] ], c++ ], {n, 1, x-2} ]; c # the values of x to use are given by A006880

Extensions

a(7)-a(9) from Jud McCranie, Oct 07 2000
a(10)-a(12) from Martin Raab, Oct 04 2006
a(13)-a(14) from Charles R Greathouse IV, Feb 09 2022
Showing 1-10 of 10 results.