A084487 - OEIS

A084487

Prime(n)+q, where q is the next prime such that q mod 4 = prime(n) mod 4.

10, 18, 18, 30, 30, 46, 42, 54, 66, 74, 78, 94, 90, 106, 114, 126, 134, 138, 150, 162, 162, 186, 186, 198, 210, 210, 234, 222, 250, 258, 270, 286, 290, 306, 314, 330, 330, 346, 354, 370, 374, 390, 390, 426, 410, 434, 450, 466, 462, 474, 490, 498, 514, 526, 534

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

OFFSET

2,1

LINKS

Harvey P. Dale, Table of n, a(n) for n = 2..1000

EXAMPLE

Prime(5) = 11, 11 mod 4 = 3, 13 mod 4 = 1, 17 mod 4 = 1, 19 mod 4 = 3, hence a(5) = 11+19 = 30.

MATHEMATICA

nq4[n_]:=Module[{q=NextPrime[n], m=Mod[n, 4]}, While[Mod[q, 4]!=m, q= NextPrime[ q]]; n+q]; Table[nq4[n], {n, Prime[Range[2, 60]]}] (* Harvey P. Dale, Aug 18 2019 *)

PROG

(PARI) {forprime(p=3, 270, m=p%4; q=nextprime(p+1); while(q%4!=m, q=nextprime(q+1)); print1(p+q, ", "))}

CROSSREFS

Cf. A084488.

Sequence in context: A156382 A214894 A368477 * A055567 A373994 A087119

Adjacent sequences: A084484 A084485 A084486 * A084488 A084489 A084490

KEYWORD

nonn

AUTHOR

Jon Perry, May 28 2003

EXTENSIONS

Edited and extended by Klaus Brockhaus, May 28 2003

STATUS

approved