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A111046 Difference between squares of twin prime pairs. 7
16, 24, 48, 72, 120, 168, 240, 288, 408, 432, 552, 600, 720, 768, 792, 912, 960, 1080, 1128, 1248, 1392, 1680, 1728, 1848, 2088, 2280, 2400, 2472, 2568, 2640, 3240, 3288, 3312, 3432, 3528, 4080, 4128, 4200, 4248, 4368, 4608, 4920, 5112, 5160, 5208, 5280 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Except for the first term 16 = 4^2, a(n) is never a square.

LINKS

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

FORMULA

a(n) = A006512(n)^2 - A001359(n)^2 = A108604(n) - A108570(n) = 2*A054735(n) = 4*A014574(n) = 8*A040040(n).

MAPLE

ZL:=[]:for p from 1 to 1400 do if (isprime(p) and isprime(p+2)) then ZL:=[op(ZL), (((p+2)^2)-p^2)]; fi; od; print(ZL); # Zerinvary Lajos, Mar 08 2007

MATHEMATICA

Select[Table[Prime[n] + 1, {n, 220}], PrimeQ[ # + 1] &] *4 (* Ray Chandler, Oct 12 2005 *)

4+4#&/@Select[Partition[Prime[Range[300]], 2, 1], #[[2]]-#[[1]]==2&] [[All, 1]] (* Harvey P. Dale, Apr 12 2018 *)

PROG

(Haskell)

a111046 = (* 2) . a054735  -- Reinhard Zumkeller, Feb 10 2015

CROSSREFS

Cf. A001359, A006512, A014574, A040040, A054735, A108570, A108604.

Sequence in context: A175161 A045875 A046434 * A205187 A162819 A029720

Adjacent sequences:  A111043 A111044 A111045 * A111047 A111048 A111049

KEYWORD

easy,nonn

AUTHOR

Giovanni Teofilatto, Oct 06 2005

EXTENSIONS

Edited and extended by Ray Chandler, Oct 12 2005

STATUS

approved

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Last modified December 9 13:50 EST 2019. Contains 329877 sequences. (Running on oeis4.)