A071256 Smallest multiple of n sandwiched between twin primes.

4, 4, 6, 4, 30, 6, 42, 72, 18, 30, 198, 12, 312, 42, 30, 192, 102, 18, 228, 60, 42, 198, 138, 72, 150, 312, 108, 420, 348, 30, 1302, 192, 198, 102, 420, 72, 1998, 228, 312, 240, 1230, 42, 1032, 660, 180, 138, 282, 192, 882, 150, 102, 312, 6360, 108, 660

Offset

1,1

Comments

Conjecture: lim sup n ->infinity a(n)/n^2 exists = C, where 0<C<1. - Benoit Cloitre, May 23 2002

Links

T. D. Noe, Table of n, a(n) for n=1..1000

Mathematica

Table[ s = 2; While[ Mod[s, n] + 2 - Boole[ PrimeQ[s - 1]] - Boole[ PrimeQ[s + 1]] > 0, s++]; s, {n, 1, 55}] (* Jean-François Alcover, Dec 08 2011, after Pari *)
With[{tpm=Mean/@Select[Partition[Prime[Range[1000]], 2, 1], #[[2]]-#[[1]] == 2&]}, Flatten[Table[Select[tpm, Divisible[#, n]&, 1], {n, 60}]]] (* Harvey P. Dale, Apr 12 2012 *)

Prog

(PARI) for(n=1, 100, s=2; while(s%n+2-isprime(s-1)-isprime(s+1)>0, s++); print1(s, ", "))

Crossrefs

Cf. A071558

Sequence in context: A339719 A276683 A247343 * A078240 A296844 A332917

Adjacent sequences: A071253 A071254 A071255 * A071257 A071258 A071259

Keyword

nice,nonn

Author

Amarnath Murthy, May 22 2002

Extensions

More terms from Benoit Cloitre, May 23 2002

Status

approved