

A036057


Friedman numbers: can be written in a nontrivial way using their digits and the operations +  * / ^ and concatenation of digits (but not of results).


10



25, 121, 125, 126, 127, 128, 153, 216, 289, 343, 347, 625, 688, 736, 1022, 1024, 1206, 1255, 1260, 1285, 1296, 1395, 1435, 1503, 1530, 1792, 1827, 2048, 2187, 2349, 2500, 2501, 2502, 2503, 2504, 2505, 2506, 2507, 2508, 2509, 2592, 2737, 2916, 3125, 3159
(list;
graph;
refs;
listen;
history;
text;
internal format)



OFFSET

1,1


COMMENTS

Mitchell's and Wilson's lists both lack two terms, 16387 = (16/8)^(7)+3 and 41665 = 641*65.  Giovanni Resta, Dec 14 2013


REFERENCES

M. Brand, Friedman numbers have density 1, Discrete Applied Mathematics, Volume 161, Issues 1617, November 2013, Pages 23892395.


LINKS

Kerry Mitchell, Table of n, a(n) for n = 1..842 [taken from Eric Friedman's page]
Ed Copeland and Brady Haran, Friedman numbers  Numberphile, 2014
Erich Friedman, Friedman Numbers
Robert G. Wilson v, Table of n, a(n) with factorizations for n=1..844
Giovanni Resta, Friedman numbers Friedman numbers and expressions up to 10^6
Index entries for Four 4's problem


FORMULA

a(n) ~ n, see Brand.  Charles R Greathouse IV, Jun 04 2013


EXAMPLE

E.g. 153=51*3, 736=3^6+7. Not 26 = 2 6, that's trivial.


CROSSREFS

Cf. A080035, A156954, A046469.
Sequence in context: A126412 A078815 A206472 * A083509 A213445 A031151
Adjacent sequences: A036054 A036055 A036056 * A036058 A036059 A036060


KEYWORD

base,nonn


AUTHOR

Erich Friedman


EXTENSIONS

Corrected broken URL. Added crossreference to A156954 R. J. Mathar, Feb 20 2009


STATUS

approved



