A099442 - OEIS

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A099442

Semiprimes of the form A000295(n)=2^n-n-1.

4, 26, 57, 247, 502, 4083, 1073741793, 4294967263, 8589934558, 70368744177617, 4503599627370443, 4611686018427387841, 18889465931478580854709, 75557863725914323419059, 77371252455336267181195177 (list; graph; refs; listen; history; internal format)

	OFFSET	`1,1`
	EXAMPLE	`a(4)=247 because 247=13*19=2^8-8-1=2^A099441(4)-A099441(4)-1.`
	CROSSREFS	`Cf. A000295 2^n-n-1 (column 2 of the Eulerian numbers), A099439 2^n-n-1 is prime, A099440 primes in A000295, A099441 2^n-n-1 is a semiprime.` `Sequence in context: A056193 A196672 A102203 * A014450 A200058 A142962` `Adjacent sequences: A099439 A099440 A099441 * A099443 A099444 A099445`
	KEYWORD	`nonn`
	AUTHOR	`Hugo Pfoertner (hugo(AT)pfoertner.org), Oct 18 2004`

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Last modified February 17 04:58 EST 2012. Contains 205985 sequences.