A131021 - OEIS

A131021

Prime semiperimeters of quadrilaterals with sides which are four consecutive primes.

13, 101, 739, 751, 1301, 1459, 1471, 1483, 1583, 1619, 1877, 1889, 1949, 2213, 2239, 2351, 2381, 2441, 2473, 2549, 2741, 2917, 3271, 3413, 3863, 4133, 4567, 4987, 5081, 5279, 5347, 5783, 5813, 6719, 7027, 7369, 7459, 7607, 8233, 8291, 9151, 9187, 9397

(list; graph; refs; listen; history; text; internal format)

OFFSET

1,1

COMMENTS

These are the prime numbers in A131019(k), occurring at k=1, 13, 71, 72, 116, 127, 128, 129, 136, 138, 157, 158, 162, 183, 185, ....

LINKS

Zak Seidov, Table of n, a(n) for n = 1..1000

FORMULA

A131019 INTERSECT A000040.

MAPLE

for n from 1 to 1000 do a131019 := add(ithprime(n+i), i=1..4)/2 : if isprime(a131019) then printf("%d, ", a131019) ; fi ; od:

MATHEMATICA

Select[(Total /@ Partition[Prime[Range[10^3]], 4, 1])/2, PrimeQ] (* Zak Seidov, Nov 01 2012 *)

PROG

(PARI) p=3; q=5; r=7; forprime(s=11, 1e4, if(isprime(t=(p+q+r+s)/2), print1(t", ")); p=q; q=r; r=s) \\ Charles R Greathouse IV, Nov 01 2012

CROSSREFS

Sequence in context: A336347 A075604 A142297 * A332907 A087595 A117653

Adjacent sequences: A131018 A131019 A131020 * A131022 A131023 A131024

KEYWORD

easy,nonn

AUTHOR

R. J. Mathar and Jonathan Vos Post, Jun 12 2007

STATUS

approved