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Search: id:A086557
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| A086557 |
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Smallest number not included earlier, beginning with 2 and having prime signature of n. |
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+0
1
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| 2, 23, 25, 29, 21, 211, 27, 289, 22, 223, 20, 227, 26, 201, 2401, 229, 28, 233, 207, 202, 203, 239, 24, 2209, 205, 2197, 212, 241, 222, 251, 243, 206, 209, 213, 225, 257, 214, 215, 232, 263, 230, 269, 236, 242, 217, 271, 208, 2809, 244, 218, 245, 277, 248, 219
(list; graph; listen)
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OFFSET
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2,1
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COMMENT
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A rearrangement of numbers beginning with 2.
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EXAMPLE
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a(24) = 232= 2^3*29 as 24 = 2^3*3.
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MAPLE
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se := {seq(20+k, k=0..9), seq(200+k, k=0..99), seq(2000+k, k=0..999), seq(20000+k, k=0..9999), seq(200000+k, k=0..99999)}: a[2] := 2:for n from 3 to 60 do l := sort(convert(se, list)): ifa := ifactors(n):no := nops(ifa[2]): prisig := sort([seq(ifa[2][j][2], j=1..no)]):h := 0:while(true) do h := h+1: ifa := ifactors(l[h]): no2 := nops(ifa[2]):prisig2 := sort([seq(ifa[2][j][2], j=1..no2)]):ok := true: if(no<>no2) then ok := false: else for w from 1 to no do if(prisig[w]<>prisig2[w]) then ok := false:break:fi:od:fi: if(ok=true) then a[n] := l[h]:se := se minus {l[h]}:break:fi:od:od:seq(a[q], q=2..60); (from Sascha Kurz)
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CROSSREFS
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Cf. A086549.
Sequence in context: A084323 A131983 A105813 this_sequence A042797 A041649 A141533
Adjacent sequences: A086554 A086555 A086556 this_sequence A086558 A086559 A086560
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KEYWORD
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base,nonn
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AUTHOR
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Amarnath Murthy (amarnath_murthy(AT)yahoo.com), Aug 30 2003
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EXTENSIONS
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Corrected and extended by Sascha Kurz (sascha.kurz(AT)uni-bayreuth.de), Sep 22 2003
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