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A089001 Numbers n such that 2*n^2 + 1 is prime. 8
1, 3, 6, 9, 21, 24, 27, 30, 33, 36, 42, 45, 66, 72, 75, 87, 93, 96, 99, 102, 105, 123, 132, 135, 153, 156, 162, 177, 186, 189, 201, 204, 219, 228, 237, 240, 255, 264, 273, 285, 297, 300, 306, 321, 324, 327, 351, 357, 360, 366, 375, 387, 393, 399, 405, 417, 423 (list; graph; refs; listen; history; internal format)
OFFSET

1,2

COMMENTS

All terms except the first one are multiples of 3. - Zak Seidov (zakseidov(AT)yahoo.com)

FORMULA

a(n)=((A090698(n)-1)/2)^(1/2).

Starting with n=2, a(n)=3*A089008(n-1). - Zak Seidov (zakseidov(AT)yahoo.com)

CROSSREFS

Cf. A089008, A090612, A090698.

Sequence in context: A018186 A015938 A116614 * A050889 A026095 A061929

Adjacent sequences:  A088998 A088999 A089000 * A089002 A089003 A089004

KEYWORD

nonn

AUTHOR

N. J. A. Sloane (njas(AT)research.att.com), Dec 20 2003

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Last modified February 16 03:44 EST 2012. Contains 205860 sequences.