login
The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A281256 Runs of consecutive integers in A270877, which is produced by a decaying trapezoidal modification of the sieve of Eratosthenes. 1
8, 13, 1, 19, 16, 4, 32, 64, 22, 49, 34, 166, 27, 71, 38, 44, 172, 59, 302, 1984, 46771, 56, 178, 94, 346, 4925, 59492, 188357, 68, 205, 352, 617, 7408, 113492, 371918, 881212, 80, 211, 382, 939, 9110, 114602, 964583, 6671161, 24365591, 89, 214, 581, 1011, 11090, 207938, 1008362 (list; table; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Square table T, read by ascending antidiagonals, where T(n,m) gives the least integer in the n-th occurrence of a run of exactly m consecutive integers in the ordered sequence A270877.

A270877 is sifted from the positive integers by modifying the sieve of Eratosthenes: instead of eliminating integers that would enumerate a rectangular area dot pattern with one side held at a constant length (equal to each surviving integer in turn), the sieve eliminates those enumerating a trapezoidal area dot pattern with the constant length being the trapezoid's longest side. Given this geometric relationship, it is considered worth looking for qualities that A270877 may have in common with the sequence of primes, potentially influenced by related causes such as the effect of prime factors on A270877.

The columns of this sequence, listing the runs of m consecutive integers within A270877, merit comparative examination with equivalent sequences for prime k-tuples. For m=5, the notably larger ratio between T(1,5) and T(2,5) resembles early large ratio gaps in the occurrence sequences of k-tuples such as A022008 (sextuples), whereas columns m<5 are more comparable with those for shorter k-tuples such as A001359 (twin primes) and A007530 (quadruples), each having a relatively low-valued first term (less than 60) and without such a large ratio gap. In comparison, the columns for runs m>5 appear more like the sequences for some longer k-tuples such as A027570 (a 10-tuple sequence). Row 1 merits comparative examination with A186702 for primes.

The author conjectures that T(n,m) exists for all n>=1, m>=1.

LINKS

Table of n, a(n) for n=1..52.

EXAMPLE

4, 5 and 6 occur in A270877, but 3 and 7 do not. This is the first run of exactly 3 consecutive integers in A270877, so T(1,3) = 4.

Square table T(n,m) begins:

   8,   1,   4,   49,    38,  46771,  188357,   881212, ...

  13,  16,  22,   71,  1984,  59492,  371918,  6671161, ...

  19,  64,  27,  302,  4925, 113492,  964583,  8799769, ...

  32, 166,  59,  346,  7408, 114602, 1008362, 13579777, ...

  34, 172,  94,  617,  9110, 207938, 1094293, 14874616, ...

  44, 178, 352,  939, 11090, 291712, 1156214, 15974752, ...

  56, 205, 382, 1011, 13007, 323716, 1239046, 20585962, ...

  68, 211, 581, 1080, 13216, 429915, 1433918, 20745838, ...

  80, 214, 599, 1091, 14710, 442807, 1702694, 24321313, ...

  89, 223, 624, 1151, 15052, 457220, 1712927, 25634557, ...

CROSSREFS

This is an analysis of A270877.

Cf. A001359, A007530, A022008, A027570, A186702.

Sequence in context: A258780 A228663 A076028 * A070476 A124159 A128662

Adjacent sequences:  A281253 A281254 A281255 * A281257 A281258 A281259

KEYWORD

nonn,tabl

AUTHOR

Peter Munn, Jan 18 2017

STATUS

approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified June 1 12:29 EDT 2020. Contains 334762 sequences. (Running on oeis4.)