id:A077462 - OEIS Search Results

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Number of prime factor configuration patterns.

+0
2

0, 1, 2, 2, 3, 2, 4, 2, 5, 3, 4, 2, 6, 2, 4, 4, 7, 2, 8, 2, 6, 4, 4, 2, 9, 3, 4, 5, 6, 2, 10, 2, 11, 4, 4, 4, 12, 2, 4, 4, 9, 2, 10, 2, 6, 6, 4, 2, 13, 3, 8, 4, 6, 2, 14, 4, 9, 4, 4, 2, 15, 2, 4, 6, 16, 4, 10, 2, 6, 4, 10, 2, 17, 2, 4, 8, 6, 4, 10, 2, 13, 7, 4, 2, 15, 4, 4, 4, 9, 2, 18, 4, 6, 4, 4, 4, 19 (list; graph; listen)

	OFFSET	`0,3`
	COMMENT	`Call two numbers equivalent if they have the same prime factorization exponent partition. This sequence enumerates the equivalence classes.` `A055932(a(n)) = A071364(n). - David Wasserman (wasserma(AT)spawar.navy.mil), Dec 21 2004`
	LINKS	`S. Whealton, Prime Factor Configuration Pattern Numbers.`
	PROGRAM	`(PARI) a(n)=local(vn); if(n<1, return(0)); vn=factor(n)[, 2]; for(i=1, n, if(vn==factor(i)[, 2], return(#Set(vector(i, j, factor(j)[, 2])))))`
	CROSSREFS	`Sequence in context: A001616 A144371 A101296 this_sequence A129294 A117658 A067540` `Adjacent sequences: A077459 A077460 A077461 this_sequence A077463 A077464 A077465`
	KEYWORD	`nonn,easy`
	AUTHOR	`Michael Somos, Nov 07 2002`

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Last modified November 25 20:09 EST 2009. Contains 167514 sequences.

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