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Search: id:A131822
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| A131822 |
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Increment each prime factor for each term of the least prime signature sequence derived from A080577. |
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+0
4
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| 1, 3, 9, 15, 27, 45, 105, 81, 135, 225, 315, 1155, 243, 405, 675, 945, 1575, 3465, 15015, 729, 1215, 2025, 2835, 3375, 4725, 10395, 11025, 17325, 45045, 255255, 2187, 3645, 6075, 8505, 10125, 14175, 31185, 23625, 33075, 51975, 135135, 121275, 225225
(list; graph; listen)
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OFFSET
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1,2
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FORMULA
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a(n)=A003961[A036035(n-1)]. - R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Nov 11 2007
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EXAMPLE
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The term 30 = 2*3*5 becomes 105 = 3*5*7
From A080577 we obtain
1
2
4, 6
8, 12, 30
16, 24, 36, 60, ...
etc.
so the sequence begins
1
3
9, 15
27, 45, 105
81, 135, 225, 315, ...
etc
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MAPLE
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A003961 := proc(n) local ifs, i ; ifs := ifactors(n)[2] ; mul(nextprime(op(1, i))^op(2, i), i=ifs) ; end: A036042 := proc(n) local a, nredu ; a := 0 ; nredu := n+1 ; while nredu > 0 do nredu := nredu-combinat[numbpart](a) ; a := a+1 ; od: RETURN(a-1) ; end: A036035 := proc(n) local row, idx, pa, a, i ; if n = 0 then 1 ; else row := A036042(n) ; idx := n-add(combinat[numbpart](i), i=0..row-1) ; pa := op(-idx-1, combinat[partition](row)) ; a := 1; for i from 1 to nops(pa) do a := a*ithprime(i)^op(-i, pa) ; od; RETURN(a) ; fi ; end: A131822 := proc(n) A003961(A036035(n-1)) ; end: seq(A131822(n), n=1..80) ; - R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Nov 11 2007
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CROSSREFS
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Cf. A080577 A131801.
Sequence in context: A089632 A082897 A147516 this_sequence A131801 A122819 A099409
Adjacent sequences: A131819 A131820 A131821 this_sequence A131823 A131824 A131825
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KEYWORD
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easy,nonn
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AUTHOR
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Alford Arnold (Alford1940(AT)aol.com), Jul 19 2007
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EXTENSIONS
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Corrected and extended by R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Nov 11 2007
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