A154674 Averages of twin prime pairs k such that k*11 and k/11 are squares.

990000, 1940400, 2227500, 6187500, 35640000, 54212400, 57182400, 74933100, 159677100, 164745900, 167310000, 194040000, 289485900, 380318400, 424205100, 496742400, 664101900, 684773100, 902919600, 976100400, 982327500, 1007433900

Offset

1,1

Links

Amiram Eldar, Table of n, a(n) for n = 1..10000

Formula

a(n) = 9900*A154774(n)^2. - M. F. Hasler, Jan 15 2009

Mathematica

lst={}; Do[If[PrimeQ[n-1]&&PrimeQ[n+1], s=(n*11)^(1/2); If[Floor[s]==s, AppendTo[lst, n]]], {n, 6, 11!, 6}]; lst...and/or... lst={}; Do[If[PrimeQ[n-1]&&PrimeQ[n+1], s=(n/11)^(1/2); If[Floor[s]==s, AppendTo[lst, n]]], {n, 6, 11!, 6}]; lst
Select[11*Range[10^4]^2, And @@ PrimeQ[# + {-1, 1}] &] (* Amiram Eldar, Dec 25 2019 *)

Prog

(PARI) for(i=1, 999, isprime(9900*i^2+1) && isprime(9900*i^2-1) && print1(9900*i^2", ")) \\ M. F. Hasler, Jan 15 2009

Crossrefs

Cf. A154670, A154671, A154672, A154673, A154774.

Sequence in context: A328287 A083395 A106782 * A236034 A055617 A055618

Adjacent sequences: A154671 A154672 A154673 * A154675 A154676 A154677

Keyword

nonn

Author

Vladimir Joseph Stephan Orlovsky, Jan 13 2009

Extensions

More terms from M. F. Hasler, Jan 15 2009

Status

approved