login
This site is supported by donations to The OEIS Foundation.

 

Logo

Annual appeal: Please make a donation to keep the OEIS running! Over 6000 articles have referenced us, often saying "we discovered this result with the help of the OEIS".
Other ways to donate

Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
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

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent | More pages
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy .

Last modified December 15 03:08 EST 2017. Contains 296020 sequences.