A075043 Primes for which the seven closest primes are smaller.

15683, 25471, 31397, 43801, 44293, 69499, 89689, 102701, 124367, 142993, 155921, 162293, 166871, 172441, 183527, 193891, 196201, 198859, 203461, 206827, 212701, 221101, 225167, 225383, 248909, 256219, 259033, 265621, 282713, 288583, 290249

Offset

1,1

Comments

If 9 consecutive primes are p1, p2, p3 ... p9, p8 is included in the sequence if p8-p1 is less than p9-p8. - Harvey P. Dale, Mar 25 2013

Links

Harvey P. Dale, Table of n, a(n) for n = 1..1000

Example

The seven closest primes to 15683 are 15679 (difference = 4), 15671 (difference = 12), 15667 (difference = 16), 15661 (difference = 22), 15649 (difference = 34) and 15647 (difference = 36). These are all smaller than 15683 so 15683 is in the list.

Mathematica

NextPrim[n_] := Block[{k = n + 1}, While[ !PrimeQ[k], k++ ]; k]; ps = {0, 0, 0, 0, 0, 0, 0, 0, 1}; Do[ps = Drop[ps, 1]; ps = Append[ps, NextPrim[ ps[[ -1]]]]; If[ ps[[ -1]] - ps[[ -2]] > ps[[ -2]] - ps[[1]], Print[ ps[[ -2]]]], {n, 1, 26185}]
 Transpose[Select[Partition[Prime[Range[25000]], 9, 1], #[[8]]-#[[1]]<#[[9]]- #[[8]]&]][[8]](* Harvey P. Dale, Mar 25 2013 *)

Crossrefs

Cf. A001223, A074979, A074982, A075030, A075037, A075038, A075050 and A075051.

Sequence in context: A373177 A165612 A206747 * A109567 A075050 A134121

Adjacent sequences: A075040 A075041 A075042 * A075044 A075045 A075046

Keyword

nonn

Author

Neil Fernandez, Oct 10 2002

Extensions

Edited and extended by Robert G. Wilson v, Oct 11 2002

Status

approved