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Search: id:A120454
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| A120454 |
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Ceiling[GPF(n)/LPF(n)] where GPF is greatest prime factor, LPF is least prime factor. |
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+0
1
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| 1, 1, 1, 1, 1, 2, 1, 1, 1, 3, 1, 2, 1, 4, 2, 1, 1, 2, 1, 3, 3, 6, 1, 2, 1, 7, 1, 4, 1, 3, 1, 1, 4, 9, 2, 2, 1, 10, 5, 3, 1, 4, 1, 6, 2, 12, 1, 2, 1, 3, 6, 7, 1, 2, 3, 4, 7, 15, 1, 3, 1, 16, 3, 1, 3, 6, 1, 9, 8, 4, 1, 2, 1, 19, 2, 10, 2, 7, 1, 3, 1, 21, 1, 4, 4, 22, 10, 6, 1, 3, 2, 12, 11, 24, 4, 2, 1, 4, 4
(list; graph; listen)
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OFFSET
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1,6
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COMMENT
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Given GPF(n) and LPF(n), the sum is A074320, the difference is A046665, and the product is A066048. a(n) = 1 iff n is p^k iff n is in A000961.
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FORMULA
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a(n) = ceiling[A006530(n)/A020639(n)].
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EXAMPLE
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a(26) = ceiling[GPF(26)/LPF(26)] = ceiling[13/2] = 7.
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MAPLE
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A120454 := proc(n) local ifs ; if n = 1 then RETURN(1) ; else ifs := ifactors(n)[2] ; RETURN( ceil(op(1, op(-1, ifs))/op(1, op(1, ifs))) ) ; fi ; end ; for n from 1 to 100 do printf("%d, ", A120454(n)) ; od ; - R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Dec 16 2006
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CROSSREFS
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Cf. A000040, A006530, A020639, A074320, A046665, A066048.
Sequence in context: A101491 A032436 A073408 this_sequence A076511 A099244 A014671
Adjacent sequences: A120451 A120452 A120453 this_sequence A120455 A120456 A120457
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KEYWORD
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easy,nonn
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AUTHOR
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Jonathan Vos Post (jvospost2(AT)yahoo.com), Aug 16 2006
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EXTENSIONS
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Corrected and extended by R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Dec 16 2006
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