id:A154893 - OEIS Search Results

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Numbers whose number of proper divisors is not a prime number.

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1, 2, 3, 5, 7, 11, 13, 16, 17, 19, 23, 29, 31, 36, 37, 41, 43, 47, 48, 53, 59, 61, 64, 67, 71, 73, 79, 80, 81, 83, 89, 97, 100, 101, 103, 107, 109, 112, 113, 120, 127, 131, 137, 139, 144, 149, 151, 157, 162, 163, 167, 168, 173, 176, 179, 181, 191, 193, 196, 197, 199 (list; graph; listen)

	OFFSET	`1,2`
	COMMENT	`Complement of A063806.`
	MATHEMATICA	`Select[Range[300], ! PrimeQ[DivisorSigma[0, # ] - 1] &] [From Stefan Steinerberger (stefan.steinerberger(AT)gmail.com), Jan 31 2009]`
	CROSSREFS	`Cf. A032741, A063806.` `Sequence in context: A062063 A167175 A026478 this_sequence A084111 A020625 A033633` `Adjacent sequences: A154890 A154891 A154892 this_sequence A154894 A154895 A154896`
	KEYWORD	`easy,nonn`
	AUTHOR	`Omar E. Pol (info(AT)polprimos.com), Jan 25 2009`
	EXTENSIONS	`More terms from Stefan Steinerberger (stefan.steinerberger(AT)gmail.com), Jan 31 2009`

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Last modified December 1 19:22 EST 2009. Contains 167811 sequences.

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