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A064101 Primes p = p(k) such that p(k) + p(k+5) = p(k+1) + p(k+4) = p(k+2) + p(k+3). 1
5, 7, 19, 31, 97, 131, 151, 293, 587, 683, 811, 839, 857, 907, 1013, 1097, 1279, 2347, 2677, 2833, 3011, 3329, 4217, 4219, 5441, 5839, 5849, 6113, 8233, 8273, 8963, 9433, 10301, 10427, 10859, 11953, 13513, 13597, 13721, 13931, 14713, 15629, 16057 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Harry J. Smith, Table of n, a(n) for n = 1..1000

EXAMPLE

The first ten primes are 2, 3, 5, 7, 11, 13, 17, 19, 23 and 29. Take just the fourth through the ninth and rearrange them such that the first pairs with the sixth, the second with the fifth and the third with the fourth as follows: 7 and 23, 11 and 19 and 13 and 17. All three pairs sum to 30. Therefore a(2) = 7.

MAPLE

A := {}: for n to 1000 do p1 := ithprime(n); p2 := ithprime(n+1); p3 := ithprime(n+2); p4 := ithprime(n+3); p5 := ithprime(n+4); p6 := ithprime(n+5); if `and`(p1+p6 = p2+p5, p2+p5 = p3+p4) then A := `union`(A, {p1}) end if end do; A := A;

MATHEMATICA

a = {0, 0, 0, 0, 0, 0}; Do[ a = Delete[ a, 1 ]; a = Append[ a, Prime[ n ] ]; If[ a[ [ 1 ] ] + a[ [ 6 ] ] == a[ [ 2 ] ] + a[ [ 5 ] ] == a[ [ 3 ] ] + a[ [ 4 ] ], Print[ a[ [ 1 ] ] ] ], {n, 1, 20000} ] (* RGWv *)

Prime[Select[Range[100], Prime[#] + Prime[# + 5] == Prime[# + 1] + Prime[# + 4] && Prime[#] + Prime[# + 5] == Prime[# + 2] + Prime[# + 3] &]]

PROG

(PARI) { n=0; default(primelimit, 1500000); for (k=1, 10^9, p1=prime(k) + prime(k + 5); p2=prime(k + 1) + prime(k + 4); p3=prime(k + 2) + prime(k + 3); if (p1==p2 && p2==p3, write("b064101.txt", n++, " ", prime(k)); if (n==1000, break)) ) } \\ Harry J. Smith, Sep 07 2009

CROSSREFS

Cf. A022885.

Sequence in context: A001562 A163386 A200178 * A018581 A146470 A296935

Adjacent sequences:  A064098 A064099 A064100 * A064102 A064103 A064104

KEYWORD

easy,nonn

AUTHOR

Robert G. Wilson v, Sep 17 2001

STATUS

approved

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Last modified August 18 07:11 EDT 2019. Contains 326072 sequences. (Running on oeis4.)