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A007547
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Number of steps to compute n-th prime in PRIMEGAME (slow version).
(Formerly M5075)
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6
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19, 69, 281, 710, 2375, 3893, 8102, 11361, 19268, 36981, 45680, 75417, 101354, 118093, 152344, 215797, 293897, 327571, 429229, 508284, 556494, 701008, 809381, 990746, 1274952, 1435957, 1531854, 1712701, 1820085, 2021938
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,1
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REFERENCES
| J. H. Conway, FRACTRAN: a simple universal programming language for arithmetic, in T. M. Cover and Gopinath, eds., Open Problems in Communication and Computation, Springer, NY 1987, pp. 4-26.
R. K. Guy, Conway's prime producing machine. Math. Mag. 56 (1983), no. 1, 26-33.
D. Olivastro, Ancient Puzzles. Bantam Books, NY, 1993, p. 21.
N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
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MAPLE
| a:= proc(n) option remember; local l, p, m, k;
l:= [17/91, 78/85, 19/51, 23/38, 29/33, 77/29, 95/23,
77/19, 1/17, 11/13, 13/11, 15/2, 1/7, 55/1]:
if n=1 then b(0):= 2; a(0):= 0 else a(n-1) fi;
p:= b(n-1);
for m do for k while not type (p*l[k], integer) do od;
p:= p*l[k];
if 2^ilog2(p)=p then break fi
od:
b(n):= p;
m + a(n-1)
end:
seq (a(n), n=1..10); # Alois P. Heinz, May 1, 2011
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PROG
| (Haskell)
import Data.List (elemIndices)
a007547 n = a007547_list !! n
a007547_list = tail $ elemIndices 2 $ map a006530 a007542_list
-- Reinhard Zumkeller, 24 Jan 2012
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CROSSREFS
| Cf. A007542, A007546.
Cf. A006530, A034785.
Sequence in context: A044538 A204675 A007546 * A010007 A172078 A196136
Adjacent sequences: A007544 A007545 A007546 * A007548 A007549 A007550
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KEYWORD
| easy,nonn,nice,changed
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AUTHOR
| N. J. A. Sloane (njas(AT)research.att.com).
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EXTENSIONS
| More terms from Alois P. Heinz (heinz(AT)hs-heilbronn.de), May 01 2011
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