|
| |
|
|
A046427
|
|
7 steps needed to reach a prime under prime factor concatenation procedure.
|
|
0
| |
|
|
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, 2169, 2176, 2192, 2198
(list; graph; refs; listen; history; internal format)
|
|
|
|
OFFSET
| 1,1
|
|
|
LINKS
| P. De Geest, Home Primes
|
|
|
MATHEMATICA
| 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
|
|
|
CROSSREFS
| Cf. A037271, A046411.
Sequence in context: A005935 A020307 A020235 * A179338 A020238 A020301
Adjacent sequences: A046424 A046425 A046426 * A046428 A046429 A046430
|
|
|
KEYWORD
| nonn,base
|
|
|
AUTHOR
| Patrick De Geest (pdg(AT)worldofnumbers.com), Jun 15 1998.
|
|
|
EXTENSIONS
| More terms from Sam Handler (sam_5_5_5_0(AT)yahoo.com), Aug 16 2006
Extended and edited by Charles R Greathouse IV (charles.greathouse(AT)case.edu), Apr 28 2010
|
| |
|
|
