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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). 13
 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 Primes in this sequence are listed in A112419. See also the subsequence A080035 of "orderly" terms, and its subset A156954. - M. F. Hasler, Jan 04 2015 LINKS M. F. Hasler, Table of n, a(n) for n = 1..844 (data from E. Friedman's page as collected by K. Mitchell, completed by the two missing terms found by G. Resta). M. Brand, Friedman numbers have density 1, Discrete Applied Mathematics, Volume 161, Issues 16-17, November 2013, Pages 2389-2395. Ed Copeland and Brady Haran, Friedman numbers, Numberphile video, 2014 Erich Friedman, Friedman Numbers Giovanni Resta, Friedman numbers Friedman numbers and expressions up to 10^6 Robert G. Wilson v, Table of n, a(n) with factorizations for n=1..844 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 (concatenated), that's trivial. CROSSREFS Cf. A080035, A156954, A046469. Sequence in context: A078815 A270368 A206472 * A083509 A343075 A339130 Adjacent sequences: A036054 A036055 A036056 * A036058 A036059 A036060 KEYWORD base,nonn AUTHOR Erich Friedman EXTENSIONS Edited by Michel Marcus and M. F. Hasler, Jan 04 2015 STATUS approved

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Last modified December 4 11:15 EST 2023. Contains 367560 sequences. (Running on oeis4.)