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A237039 Semiprimes of the form (2p)^3 + 1, where p is prime. 6
65, 217, 10649, 195113, 1191017, 45882713, 55742969, 946966169, 2106997769, 2289529433, 2548895897, 10735357817, 26946035993, 54958685609, 77199941513, 131561576057, 132495001193, 440016501017, 456888832409, 623273556089, 848202406697, 966188398457 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Table of n, a(n) for n=1..22.

Eric Weisstein's World of Mathematics, Semiprime

Wikipedia, Semiprime

FORMULA

a(n) = (2*A237038(n))^3 + 1.

EXAMPLE

(2*2)^3 + 1 = 65 = 5*13 is a semiprime, so a(1) = 2.

MATHEMATICA

L = Select[Range[5000], PrimeQ[#] && PrimeQ[(2 #)^2 - 2 # + 1] && PrimeQ[2 # + 1] &]; (2 L)^3 + 1

CROSSREFS

Cf. A001358, A046315, A081256, A096173, A096174, A237037, A237038, A237040.

Sequence in context: A175795 A056777 A048512 * A038637 A158686 A115342

Adjacent sequences:  A237036 A237037 A237038 * A237040 A237041 A237042

KEYWORD

nonn

AUTHOR

Jonathan Sondow, Feb 02 2014

STATUS

approved

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Last modified January 19 21:35 EST 2018. Contains 297938 sequences.