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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 = (1-6/8)^(-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 16-17, November 2013, Pages 2389-2395.

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 cross-reference to A156954 R. J. Mathar, Feb 20 2009

STATUS

approved

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Last modified November 28 21:04 EST 2014. Contains 250406 sequences.