

A161594


a(n) = R(f(n)), where R = A004086 = reverse (decimal) digits, f = A071786 = reverse digits of prime factors.


12



1, 2, 3, 4, 5, 6, 7, 8, 9, 1, 11, 21, 13, 41, 51, 61, 17, 81, 19, 2, 12, 22, 23, 42, 52, 26, 72, 82, 29, 3, 31, 23, 33, 241, 53, 63, 37, 281, 39, 4, 41, 24, 43, 44, 54, 46, 47, 84, 94, 5, 312, 421, 53, 45, 55, 65, 372, 481, 59, 6, 61, 62, 36, 46, 551, 66, 67, 482, 69, 7, 71, 27
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OFFSET

1,2


COMMENTS

Might be called TITO(n), turning n inside out then turning outside in.
Here is the operation: take a number n and find its prime factors. Reverse the digits of every prime factor (for example, replace 17 by 71). Multiply the factors respecting multiplicities. For example, if the original number was 17^2*43^3, the new product will be 71^2*34^3. After that, reverse the resulting number.


LINKS

M. F. Hasler, Table of n, a(n) for n=1,...,5000. [From M. F. Hasler, Jun 24 2009]
T. Khovanova, Turning Numbers Inside Out [From Tanya Khovanova, Jul 07 2009]


FORMULA

a(p) = p, for prime p.
a(A161598(n)) <> A161598(n); a(A161597(n)) = A161597(n); A010051(a(A161600(n))) = 1.
Comment from M. F. Hasler, Jun 25 2009: a( p*10^k ) = p for any prime p.
Proof: * if gcd( p, 2*5) = 1, then a( p * 10^k ) = R( R(p) * R(2)^k * R(5)^k ) = R( R(p) * 10^k ) = R(R(p)) = p
* if gcd(p, 2*5) = 2, then p=2 and a( p * 10^k ) = R( R(2)^(k+1) * R(5)^k ) = R( 2 * 10^k ) = 2 = p and mutatis mutandis for gcd(p, 2*5) = 5.


EXAMPLE

a(34) = 241, because 34 = 2*17, f(34) = 2*71 = 142, and reversing gives 241.


MAPLE

read("transforms") ; A071786 := proc(n) local ifs, a, d ; ifs := ifactors(n)[2] ; a := 1 ; for d in ifs do a := a*digrev(op(1, d))^op(2, d) ; od: a ; end: A161594 := proc(n) digrev(A071786(n)) ; end: seq(A161594(n), n=1..80) ; # R. J. Mathar, Jun 16 2009


MATHEMATICA

reversepower[{n_, k_}] := FromDigits[Reverse[IntegerDigits[n]]]^k f[n_] := FromDigits[ Reverse[IntegerDigits[Times @@ Map[reversepower, FactorInteger[n]]]]] Table[f[n], {n, 100}]


PROG

(PARI) R=A004086; A161594(n)={n=factor(n); n[, 1]=apply(R, n[, 1]); R(factorback(n))} \\ M. F. Hasler, Jun 24 2009. Removed code for R here, see A004086 for most recent & efficient version.  M. F. Hasler, May 11 2015
(Haskell) a161594 = a004086 . a071786  Reinhard Zumkeller, Oct 14 2011


CROSSREFS

Cf. A161597, A161598, A161600, A071786, A004086, A151764.
Sequence in context: A004151 A151765 A107603 * A084011 A004086 A121760
Adjacent sequences: A161591 A161592 A161593 * A161595 A161596 A161597


KEYWORD

nonn,base,nice,look


AUTHOR

J. H. Conway & Tanya Khovanova, Jun 14 2009


EXTENSIONS

Simpler definition from R. J. Mathar, Jun 16 2009
Edited by N. J. A. Sloane, Jun 23 2009


STATUS

approved



