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.

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A201251 Record (maximal) gaps between prime septuplets (p, p+2, p+8, p+12, p+14, p+18, p+20).

Original entry on oeis.org

83160, 195930, 341880, 5414220, 9270030, 18980220, 25622520, 36077370, 51597630, 92184750, 125523090, 140407470, 141896370, 336026460, 403369470, 435390270, 442452570, 627852330, 754383210, 1008582120, 1021464990, 1073692620, 1088148810, 1145336850
Offset: 1

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Author

Alexei Kourbatov, Nov 28 2011

Keywords

Comments

Prime septuplets (p, p+2, p+8, p+12, p+14, p+18, p+20) are one of the two types of densest permissible constellations of 7 primes (A022009 and A022010). Average gaps between prime k-tuples can be deduced from the Hardy-Littlewood k-tuple conjecture and are O(log^k(p)), with k=7 for septuplets. 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^8(p)).
A201252 lists initial primes in septuplets (p, p+2, p+8, p+12, p+14, p+18, p+20) preceding the maximal gaps. A233038 lists the corresponding primes at the end of the maximal gaps.

Examples

			The gap of 83160 between septuplets starting at p=5639 and p=88799 is the very first gap, so a(1)=83160. The gap of 195930 between septuplets starting at p=88799 and p=284729 is a maximal gap - larger than any preceding gap; therefore a(2)=195930. The next gap of 341880 is again a maximal gap, so a(3)=341880. The next gap is smaller, so it does not contribute to the sequence.
		

Crossrefs

Cf. A022010 (prime septuplets p, p+2, p+8, p+12, p+14, p+18, p+20), A113274, A113404, A200503, A201062, A201073, A201596, A201598, A202281, A202361, A201051, A002386, A233038.

Formula

Gaps between prime septuplets (p, p+2, p+8, p+12, p+14, p+18, p+20) are smaller than 0.02*(log p)^8, where p is the prime at the end of the gap. There is no rigorous proof of this formula. The O(log^8(p)) growth rate is suggested by numerical data and heuristics based on probability considerations.

A233038 Primes p in prime septuplets (p, p+2, p+8, p+12, p+14, p+18, p+20) at the end of the maximal gaps in A201251.

Original entry on oeis.org

88799, 284729, 626609, 6560999, 17843459, 42981929, 69156539, 124066079, 208729049, 615095849, 832143449, 1730416139, 2488117769, 3693221669, 12171651629, 31152738299, 34230869579, 63550891499, 69428293379, 89858819579, 164310445289, 197856064319
Offset: 1

Views

Author

Alexei Kourbatov, Dec 08 2013

Keywords

Comments

Prime septuplets (p, p+2, p+8, p+12, p+14, p+18, p+20) are one of the two types of densest permissible constellations of 7 primes. Maximal gaps between septuplets of this type are listed in A201251; see comments and formulas there.

Examples

			The gap of 83160 between septuplets starting at p=5639 and p=88799 is the very first gap, so a(1)=88799. The gap of 195930 between septuplets starting at p=88799 and p=284729 is a maximal (record) gap - larger than any preceding gap; therefore a(2)=284729. The next gap of 341880 ending at 626609 is again a record, so a(3)=626609. The next gap is smaller, so that gap does not contribute a new term to the sequence.
		

Crossrefs

Extensions

Terms a(11) and beyond from b-file by Andrew Howroyd, Feb 05 2018
Showing 1-2 of 2 results.