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 1-4 of 4 results.

A027569 Initial members of prime decaplets (p, p+2, p+6, p+8, p+12, p+18, p+20, p+26, p+30, p+32).

Original entry on oeis.org

11, 33081664151, 83122625471, 294920291201, 573459229151, 663903555851, 688697679401, 730121110331, 1044815397161, 1089869189021, 1108671297731, 1235039237891, 1291458592421, 1738278660731
Offset: 1

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Author

Keywords

Comments

All terms are congruent to 11 (modulo 210). - Matt C. Anderson, May 28 2015

Crossrefs

Programs

  • Maple
    composite_small := proc (n::integer)
    description "procedure to determine if n has a prime factor less than 100";
    if igcd(2305567963945518424753102147331756070, n) = 1 then
    return false else return true end if;
    end proc;
    # begin initialization section
    p := [0, 2, 6, 8, 12, 18, 20, 26, 30, 32]; o := [1271, 1691]; m := 2310;
    # end initialization section
    with(ArrayTools); os := Size(o, 2); ps := Size(p, 2);
    loopstop := 10^11; loopstart := 0;
    print(11);
    for n from loopstart to loopstop do
    for a to os do
    counter := 0; wc := 0; wd := 0;
    while `and`(wd > -10, wd < ps) do
    wd := wd+1;
    if composite_small(m*n+o[a]+p[wd]) = false then wd := wd+1 else wd := -10 end if;
    end do;
    if wd >= 9 then while `and`(counter >= 0, wc < ps) do
    wc := wc+1;
    if isprime(m*n+o[a]+p[wc]) then counter := counter+1 else counter := -1 end if end do;
    end if;
    if counter = ps then print(m*n+o[a]); end if;
    end do;
    end do;
    # Matt C. Anderson, Apr 30 2015
  • PARI
    is(n)=isprime(n) && isprime(n+2) && isprime(n+6) && isprime(n+8) && isprime(n+12) && isprime(n+18) && isprime(n+20) && isprime(n+26) && isprime(n+30) && isprime(n+32)
    v=primes(10); t=1; forprime(p=31,1e11, v[t]=p; t=(t%10)+1; if(p-v[t]==32 && is(v[t]), print1(v[t]", "))) \\ Charles R Greathouse IV, May 20 2015
    
  • Perl
    use ntheory ":all"; say for sieve_prime_cluster(1,1e13, 2,6,8,12,18,20,26,30,32); # Dana Jacobsen, Sep 30 2015

A213647 Initial members of prime 11-tuplets: primes p such that p + (0, 2, 6, 8, 12, 18, 20, 26, 30, 32, 36) are all prime.

Original entry on oeis.org

11, 7908189600581, 10527733922591, 12640876669691, 38545620633251, 43564522846961, 60268613366231, 60596839933361, 71431649320301, 79405799458871, 109319665100531, 153467532929981, 171316998238271, 216585060731771, 254583955361621, 259685796605351, 268349524548221
Offset: 1

Views

Author

Matt C. Anderson, Jun 17 2012

Keywords

Comments

0, 2, 6, 8, 12, 18, 20, 26, 30, 32, 36 are the first terms of A135311.
All terms are congruent to 11 (modulo 210). - Zak Seidov, Sep 15 2014
Subsequence of A202282. - Zak Seidov, Sep 15 2014
All terms, except the first one, are congruent to 1271 (modulo 2310). - Matt C. Anderson, May 29 2015

Crossrefs

Programs

  • Perl
    use ntheory ":all"; say for sieve_prime_cluster(1,1e14, 2,6,8,12,18,20,26,30,32,36); # Dana Jacobsen, Oct 01 2015

Extensions

a(89) corrected by Dana Jacobsen, Oct 01 2015

A202281 Record (maximal) gaps between prime decuplets (p+0,2,6,8,12,18,20,26,30,32).

Original entry on oeis.org

33081664140, 50040961320, 211797665730, 278538937950, 314694286830, 446820068310, 589320949140, 1135263664920, 1154348695500, 1280949740070, 1340804150070, 1458168320490, 1539906870810, 1858581264540, 2590180927950, 3182865274050, 4949076176310, 5719502339670
Offset: 1

Views

Author

Alexei Kourbatov, Dec 15 2011

Keywords

Comments

Prime decuplets (p+0,2,6,8,12,18,20,26,30,32) are one of the two types of densest permissible constellations of 10 primes (A027569 and A027570).
Average gaps between prime k-tuples are O(log^k(p)), with k=10 for decuplets, by the Hardy-Littlewood k-tuple conjecture. If a gap is larger than any preceding gap, we call it a maximal gap, or a record gap. Maximal gaps may be significantly larger than average gaps; this sequence suggests that maximal gaps are O(log^11(p)).
A202282 lists initial primes in decuplets (p+0,2,6,8,12,18,20,26,30,32) preceding the maximal gaps.

Examples

			The gap of 33081664140 after the first decuplet starting at p=11 is the term a(1). The next three gaps of 50040961320, 211797665730, 278538937950 form an increasing sequence, each setting a new record; therefore each of these gaps is in the sequence, as a(2), a(3), a(4). The next gap is not a record, so it is not in this sequence.
		

Crossrefs

Cf. A027569 (prime decuplets p+0,2,6,8,12,18,20,26,30,32), A202282, A202361, A113274, A113404, A200503, A201596, A201598, A201062, A201073, A201051, A201251

Programs

Formula

(1) Upper bound: gaps between prime decuplets (p+0,2,6,8,12,18,20,26,30,32) are smaller than 0.00059*(log p)^11, where p is the prime at the end of the gap.
(2) Estimate for the actual size of maximal gaps near p: max gap = a(log(p/a)-0.2), where a = 0.00059(log p)^10 is the average gap between 10-tuples near p.
Both formulas (1) and (2) are derived from the Hardy-Littlewood k-tuple conjecture via probability-based heuristics relating the expected maximal gap size to the average gap. Neither of the formulas has a rigorous proof.

A202362 Initial prime in prime decuplets (p+0,2,6,12,14,20,24,26,30,32) preceding the maximal gaps in A202361.

Original entry on oeis.org

9853497737, 22741837817, 242360943257, 1418575498577, 4396774576277, 8639103445097, 11105292314087, 12728490626207, 119057768524127, 226608256438997, 581653272077387, 896217252921227, 987041423819807, 1408999953009347, 1419018243046487, 2189095026865907
Offset: 1

Views

Author

Alexei Kourbatov, Dec 18 2011

Keywords

Comments

Prime decuplets (p+0,2,6,12,14,20,24,26,30,32) are one of the two types of densest permissible constellations of 10 primes. Maximal gaps between decuplets of this type are listed in A202361; see more comments there.

Examples

			The gap of 12102794130 between the very first decuplets starting at p=9853497737 and p=21956291867 means that the initial term is a(1)=9853497737.
The next gap after the decuplet starting at p=21956291867 is smaller, so it does not contribute to this sequence.
The next gap of 141702673770 between the decuplets at p=22741837817 and p=164444511587 is a new record; therefore the next term is a(2)=22741837817.
		

Crossrefs

Cf. A027570 (prime decuplets p+0,2,6,12,14,20,24,26,30,32), A202281, A202282, A202361.

Programs

Showing 1-4 of 4 results.