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A077462
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Number of prime factor configuration patterns.
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1
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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; refs; listen; history; internal format)
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OFFSET
| 0,3
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COMMENTS
| 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
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LINKS
| S. Whealton, Prime Factor Configuration Pattern Numbers.
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PROG
| (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])))))
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CROSSREFS
| Sequence in context: A144371 A101296 A181819 * A129294 A117658 A067540
Adjacent sequences: A077459 A077460 A077461 * A077463 A077464 A077465
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KEYWORD
| nonn,easy
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AUTHOR
| Michael Somos, Nov 07 2002
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