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A084920 (prime(n)-1)*(prime(n)+1). +0
9
3, 8, 24, 48, 120, 168, 288, 360, 528, 840, 960, 1368, 1680, 1848, 2208, 2808, 3480, 3720, 4488, 5040, 5328, 6240, 6888, 7920, 9408, 10200, 10608, 11448, 11880, 12768, 16128, 17160, 18768, 19320, 22200, 22800, 24648, 26568, 27888, 29928 (list; graph; listen)
OFFSET

1,1

COMMENT

a(n)=A006093(n)*A008864(n);

a(n)=A084921(n)*2 for n>1; a(n)=A084922(n)*6 for n>2.

a(n)=prime(n)^2-1. [From Vladimir Orlovsky (4vladimir(AT)gmail.com), Oct 17 2009]

FORMULA

product_{n=1,2,..infinity} a(n)/A066872(n) = 2/5. a(n) = A001248(n)-1. [From R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Feb 01 2009]

MATHEMATICA

f[n_]:=Prime[n]^2-1; lst={}; Do[AppendTo[lst, f[n]], {n, 5!}]; lst [From Vladimir Orlovsky (4vladimir(AT)gmail.com), Oct 17 2009]

CROSSREFS

Cf. A000040, A005563.

Sequence in context: A065083 A037450 A081990 this_sequence A026556 A096001 A080097

Adjacent sequences: A084917 A084918 A084919 this_sequence A084921 A084922 A084923

KEYWORD

nonn

AUTHOR

Reinhard Zumkeller (reinhard.zumkeller(AT)gmail.com), Jun 11 2003

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Last modified November 24 23:16 EST 2009. Contains 167481 sequences.


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