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A064158 Integers n such that (x1*x2*..xk)^(x1+x2+..xk) = (x1+x2+..xk)^(x1*x2*...xk) where x1x2..xk are the digits of n in base 10. 2
1, 2, 3, 4, 5, 6, 7, 8, 9, 22, 112, 121, 123, 132, 211, 213, 231, 312, 321, 1124, 1142, 1214, 1241, 1412, 1421, 2114, 2141, 2411, 4112, 4121, 4211, 11125, 11133, 11152, 11215, 11222, 11251, 11313, 11331, 11512, 11521, 12115, 12122, 12151, 12212 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,2
COMMENTS
With the exception of only 112,121, and 211, each term of this sequence satisfies (sum of digits) equals (product of digits). For 112, 121, and 211, the sum of the digits is 4, the product of the digits is 2, and the terms qualify because 2^4 equals 4^2. [From Harvey P. Dale, Sep 30 2011]
LINKS
EXAMPLE
22 belongs to the sequence because (2*2)^(2+2)=(2+2)^(2*2)
MATHEMATICA
okQ[n_]:=Module[{idn=IntegerDigits[n], t, p}, t= Times@@idn; p=Total[idn]; t^p==p^t]; Select[Range[12500], okQ]
CROSSREFS
Sequence in context: A232709 A249334 A338257 * A064702 A034710 A305257
KEYWORD
easy,nonn,base
AUTHOR
Felice Russo, Sep 14 2001
EXTENSIONS
More terms from Jason Earls, Dec 04 2001
STATUS
approved

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Last modified May 29 05:33 EDT 2024. Contains 372921 sequences. (Running on oeis4.)