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A154676 Numbers n = 103*k^2 such that (n-1,n+1) is a twin prime pair (thus k = 6*m). 5
2317500, 12047292, 26163648, 43250112, 47347452, 61704828, 168228252, 333720000, 351755712, 426127068, 513127872, 840143808, 979638768, 998790588, 1089276912, 1330434108, 1357220700, 1388809152, 1694467008, 1927570428, 1986835392, 2035992348, 2136108348, 2858437872, 3070594800, 3241626300, 3903322608 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Original definition: Averages of twin prime pairs n such that n*103 and n/103 are squares.

All terms are of the form 3708*n^2. - Zak Seidov, Jan 15 2009

Obviously n*103 is a square iff n/103 is a square, say k^2. But n=103k^2 can't be the average of a twin prime pair unless it's a multiple of 6, thus k=6m and n=103*36*m^2. - M. F. Hasler, Apr 11 2009

LINKS

Table of n, a(n) for n=1..27.

MATHEMATICA

lst={}; Do[If[PrimeQ[n-1]&&PrimeQ[n+1], s=(n*103)^(1/2); If[Floor[s]==s, AppendTo[lst, n]]], {n, 9!, 2*11!, 6}]; lst (*...and/or...*) lst={}; Do[If[PrimeQ[n-1]&&PrimeQ[n+1], s=(n/103)^(1/2); If[Floor[s]==s, AppendTo[lst, n]]], {n, 9!, 2*11!, 6}]; lst

PROG

(PARI) forstep(k=0, 1e4, 6, isprime(k^2*103+1) & isprime(k^2*103-1) & print1(k^2*103, ", ")) \\ - M. F. Hasler, Apr 11 2009

CROSSREFS

Cf. A154670, A154671, A154672, A154673, A154674, A154675.

Sequence in context: A252395 A256733 A210493 * A250926 A278200 A246226

Adjacent sequences:  A154673 A154674 A154675 * A154677 A154678 A154679

KEYWORD

nonn,less

AUTHOR

Vladimir Joseph Stephan Orlovsky, Jan 14 2009

EXTENSIONS

Edited and extended by M. F. Hasler, Apr 11 2009

STATUS

approved

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Last modified November 21 17:44 EST 2017. Contains 295004 sequences.