A072541 List of pairs of numbers (k, k+4), where k-1 and k+3 are primes.

4, 8, 8, 12, 14, 18, 20, 24, 38, 42, 44, 48, 68, 72, 80, 84, 98, 102, 104, 108, 110, 114, 128, 132, 164, 168, 194, 198, 224, 228, 230, 234, 278, 282, 308, 312, 314, 318, 350, 354, 380, 384, 398, 402, 440, 444, 458, 462, 464, 468, 488, 492, 500, 504, 614, 618

Offset

1,1

Comments

The puzzle started with a(3): 8, 12, 14, 18, 20, 24, ?.

References

Frankfurter Allgemeine Sonntagszeitung, Jul 28, 2002, "Koennen Sie folgen?", p. 56.

Links

Reinhard Zumkeller, Table of n, a(n) for n = 1..10000

Formula

a(2*n-1) = A023200(n)+1, a(2*n) = A023200(n)+5, n>0.

Mathematica

Flatten[{#, #+4}&/@Select[Range[700], AllTrue[#+{-1, 3}, PrimeQ]&]] (* The program uses the AllTrue function from Mathematica version 10 *) (* Harvey P. Dale, Jul 22 2014 *)

Prog

(Haskell)
import Data.List (transpose)
a072541 n = a072541_list !! (n-1)
a072541_list = concat $ transpose
               [map (+ 1) a023200_list, map (+ 5) a023200_list]
-- Reinhard Zumkeller, Aug 01 2014

Crossrefs

Cf. A023200.

Sequence in context: A272812 A273207 A145154 * A141719 A098352 A273395

Adjacent sequences: A072538 A072539 A072540 * A072542 A072543 A072544

Keyword

nonn

Author

Reinhard Zumkeller, Aug 04 2002

Status

approved