The OEIS is supported by the many generous donors to the OEIS Foundation.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A226095 Primes formed by concatenation (exponent then prime) of prime factorizations of the positive integers. 1
 13, 1213, 17, 23, 2213, 113, 1217, 1223, 12113, 131, 137, 12119, 22111, 3217, 167, 173, 179, 43, 221317, 12143, 22123, 197, 1103, 1109, 4217, 22129, 17117, 211, 12161, 32117, 13147, 1327, 1151, 32119, 23117, 15131, 17123, 1163, 1213129, 13159, 1181, 1217113 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS This produces primes well above the base composite, like 22111 from 44. Entries stemming strictly from composite prime factorizations will be unique and the sequence will very likely be infinite. Of course not every prime will be encountered, and duplication will be seen across composite and prime factorization treated jointly (an example being 18 and 223 both yielding the prime 1223). Primes in A123132. - Charles R Greathouse IV, May 28 2013 LINKS T. D. Noe, Table of n, a(n) for n = 1..10000 EXAMPLE 44 = 2^2 * 11^1 yields 22111, which is prime and so enters the sequence.  Powers precede the prime factor. MAPLE select(isprime, [seq((l-> parse(cat(seq([i[2], i[1]][], i=l))))(sort(ifactors(n)[2], (x, y)-> x[1]

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

Last modified May 26 04:43 EDT 2022. Contains 354074 sequences. (Running on oeis4.)