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A112419 Prime Friedman numbers. 2
127, 347, 2503, 12101, 12107, 12109, 15629, 15641, 15661, 15667, 15679, 16381, 16447, 16759, 16879, 19739, 21943, 27653, 28547, 28559, 29527, 29531, 32771, 32783, 35933, 36457, 39313, 39343, 43691, 45361, 46619, 46633, 46643, 46649, 46663, 46691, 48751, 48757, 49277, 58921, 59051, 59053, 59263, 59273, 64513, 74353, 74897, 78163, 83357 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

A Friedman number is one which is expressible in a nontrivial manner with the same digits by means of the arithmetic operations +, -, *, "divided by" along with ^ and digit concatenation.

Ron Kaminsky notes that, by Dirichlet's theorem, this sequence is infinite; see Friedman link. - Charles R Greathouse IV, Apr 30 2010

There are only 49 terms below 10^5, and there are less than 40 "orderly" terms (in A080035) below 10^6. - M. F. Hasler, Jan 03 2015

LINKS

Table of n, a(n) for n=1..49.

Erich Friedman, Problem of the Month (August 2000).

FORMULA

Intersection of A036057 and A000040. - M. F. Hasler, Jan 03 2015

EXAMPLE

Since the following primes have expressions 16381 = (1+1)^(6+8) - 3 ; 16447 = -1+64+4^7 ; 16759 = 7^5 - 6*(9-1), they are in the sequence.

CROSSREFS

Cf. A036057.

Sequence in context: A283622 A080035 A162004 * A142201 A142889 A095312

Adjacent sequences:  A112416 A112417 A112418 * A112420 A112421 A112422

KEYWORD

nonn,base

AUTHOR

Lekraj Beedassy, Jan 23 2007

EXTENSIONS

Corrected and extended by Ray Chandler, Apr 24 2010

STATUS

approved

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Last modified October 23 03:37 EDT 2018. Contains 316519 sequences. (Running on oeis4.)