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A133048 Powerback(n): reverse the decimal expansion of n, drop any leading zeros, then apply the powertrain map of A133500 to the resulting number. 9
0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 1, 1, 2, 3, 4, 5, 6, 7, 8, 9, 2, 1, 4, 9, 16, 25, 36, 49, 64, 81, 3, 1, 8, 27, 64, 125, 216, 343, 512, 729, 4, 1, 16, 81, 256, 625, 1296, 2401, 4096, 6561, 5, 1, 32, 243, 1024, 3125, 7776, 16807, 32768, 59049, 6, 1, 64, 729, 4096, 15625, 46656, 117649 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,3

COMMENTS

a(A221221(n)) = A133500(A221221(n)) = A222493(n). - Reinhard Zumkeller, May 27 2013

LINKS

N. J. A. Sloane, Table of n, a(n) for n = 0..10000

EXAMPLE

E.g. 240 -> (0)42 -> 4^2 = 16; 12345 -> 54321 -> 5^4*3^2*1 = 5625.

MAPLE

powerback:=proc(n) local a, i, j, t1, t2, t3;

if n = 0 then RETURN(0); fi;

t1:=convert(n, base, 10); t2:=nops(t1);

for i from 1 to t2 do if t1[i] > 0 then break; fi; od:

a:=1; t3:=t2-i+1;

for j from 0 to floor(t3/2)-1 do a := a*t1[i+2*j]^t1[i+2*j+1]; od:

if t3 mod 2 = 1 then a:=a*t1[t2]; fi;

RETURN(a); end;

PROG

(Haskell)

a133048 0 = 0

a133048 n = train $ dropWhile (== 0) $ a031298_row n where

   train []       = 1

   train [x]      = x

   train (u:v:ws) = u ^ v * (train ws)

-- Reinhard Zumkeller, May 27 2013

CROSSREFS

Cf. A131571 (fixed points), A133059 and A133134 (records); A133500 (powertrain).

Cf. A133144 (length of trajectory), A031346 and A003001 (persistence).

Cf. A031298.

Sequence in context: A004427 A113230 A065881 * A214950 A054055 A067456

Adjacent sequences:  A133045 A133046 A133047 * A133049 A133050 A133051

KEYWORD

nonn,base

AUTHOR

J. H. Conway and N. J. A. Sloane, Dec 31 2007

STATUS

approved

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Last modified December 9 02:36 EST 2016. Contains 278959 sequences.