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Search: id:A046427
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| A046427 |
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7 steps needed to reach a prime under prime factor concatenation procedure. |
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+0
1
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| 91, 128, 196, 305, 344, 416, 438, 456, 554, 656, 690, 707, 746, 750, 779, 897, 910, 950, 1014, 1060, 1098, 1122, 1199, 1209, 1247, 1380, 1507, 1545, 1606, 1679, 1680, 1700, 1711, 1769, 1833, 1884, 1887, 1888, 1928, 1971, 1984, 2000
(list; graph; listen)
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OFFSET
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0,1
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LINKS
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P. De Geest, Home Primes
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MATHEMATICA
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numberSteps[x_]:=Module[{n, steps, digits, i}, n=x; steps=0; While[ !PrimeQ[n]&&steps<10, factors=FactorInteger[n]; digits={}; For[i=1, i<=Length[factors], i++, digits=Join[digits, Flatten[ Table[IntegerDigits[factors[[i, 1]]], {factors[[i, 2]]}]]]; ]; n=FromDigits[digits]; steps++; ]; Return[steps]]; For[i=1, i<2000, i++, If[numberSteps[i]==7, Print[i]; ]; ]; - Sam Handler (sam_5_5_5_0(AT)yahoo.com), Aug 16 2006
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CROSSREFS
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Cf. A037271, A046411.
Sequence in context: A005935 A020307 A020235 this_sequence A020238 A020301 A083517
Adjacent sequences: A046424 A046425 A046426 this_sequence A046428 A046429 A046430
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KEYWORD
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nonn,more
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AUTHOR
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Patrick De Geest (pdg(AT)worldofnumbers.com), Jun 15 1998.
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EXTENSIONS
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More terms from Sam Handler (sam_5_5_5_0(AT)yahoo.com), Aug 16 2006
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