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A133500
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Powertrain(n): if abcd... is the decimal expression of a number n, then the powertrain of n is the number n' = a^b*c^d* ..., which ends in an exponent or a base according as the number of digits is even or odd. a(0) = 0 by convention.
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17
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0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 2, 4, 8, 16, 32, 64, 128, 256, 512, 1, 3, 9, 27, 81, 243, 729, 2187, 6561, 19683, 1, 4, 16, 64, 256, 1024, 4096, 16384, 65536, 262144, 1, 5, 25, 125, 625, 3125, 15625, 78125, 390625, 1953125, 1, 6, 36, 216, 1296
(list; graph; refs; listen; history; internal format)
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OFFSET
| 0,3
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COMMENTS
| We take 0^0 = 1.
The fixed points are in A135385.
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LINKS
| N. J. A. Sloane, Table of n, a(n) for n = 0..10000
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MAPLE
| powertrain:=proc(n) local a, i, n1, n2, t1, t2; n1:=abs(n); n2:=sign(n); t1:=convert(n1, base, 10); t2:=nops(t1); a:=1; for i from 0 to floor(t2/2)-1 do a := a*t1[t2-2*i]^t1[t2-2*i-1]; od: if t2 mod 2 = 1 then a:=a*t1[1]; fi; RETURN(n2*a); end; - N. J. A. Sloane (njas(AT)research.att.com), Dec 03 2007
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CROSSREFS
| Cf. A133501-A133502, A135385. For records see A133504, A133505.
Cf. A133048 (powerback), A031346 and A003001 (persistence).
Sequence in context: A175400 A175399 A075877 * A052423 A126616 A121042
Adjacent sequences: A133497 A133498 A133499 * A133501 A133502 A133503
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KEYWORD
| nonn,base
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AUTHOR
| John Conway, Dec 03 2007
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