A124106 - OEIS

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A124106

Octagonal numbers equal to S*(3S - 2) with 3S - 2 = k^2 and S semiprime.

96, 225, 1408, 3400, 9633, 22016, 43681, 53600, 93633, 130625, 152776, 205408, 308481, 446216, 696008, 1493896, 1628033, 3280256, 4617761, 4928008, 5595136, 6720033, 8473921, 11721633, 19995008, 20919361, 22863841, 30752008, 33340000 (list; graph; refs; listen; history; internal format)

	OFFSET	`1,1`
	LINKS	`Eric Weisstein's World of Mathematics, Octagonal Number.` `Eric Weisstein's World of Mathematics, Semiprime.` `Eric Weisstein's World of Mathematics, 16-Cell`
	FORMULA	`a(n) = A112392(n)*A112393(n).`
	CROSSREFS	`Cf. A112392, A112393.` `Sequence in context: A110231 A108609 A125511 * A202898 A202891 A202591` `Adjacent sequences: A124103 A124104 A124105 * A124107 A124108 A124109`
	KEYWORD	`easy,nonn`
	AUTHOR	`Giovanni Teofilatto (g.teofilatto(AT)tiscalinet.it), Dec 13 2006, Dec 14 2006`

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Last modified February 14 23:53 EST 2012. Contains 205689 sequences.