login
The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

 

Logo

Year-end appeal: Please make a donation to the OEIS Foundation to support ongoing development and maintenance of the OEIS. We are now in our 56th year, we are closing in on 350,000 sequences, and we’ve crossed 9,700 citations (which often say “discovered thanks to the OEIS”).

Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A053008 Primes from products of split even-digit primes. 2
3, 7, 3, 7, 103, 109, 103, 409, 601, 109, 709, 907, 523, 139, 193, 853, 379, 397, 739, 937, 499, 223, 499, 1621, 2161, 6121, 6211, 4261, 4621, 6421, 2017, 2551, 5521, 139, 193, 769, 967, 997, 109, 3001, 1039, 1093, 3019, 3109, 9013, 9103, 4111, 1153, 1531 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

REFERENCES

C. A. Pickover, chapter 30 of Keys to Infinity. NY: Wiley, 1995. Pages 227-231.

LINKS

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

Sean A. Irvine, Java program (github)

FORMULA

Take even-digit primes, split digits into two halves, multiply the halves and form primes by rearranging digits. If split in right half results in a leading zero, that prime is skipped.

If more than one prime can be formed from the digits of the product, then each appears in numerical order. Consequently this sequence is not in one-to-one correspondence with the terms of A053009 and A053010. - Sean A. Irvine, Dec 02 2021

EXAMPLE

103 is a term because from the prime 1013 we get 10 and 13 after the split; 10*13=130 and the digits 1 3 0 can be arranged to form 103, prime.

CROSSREFS

Cf. A053009, A053010.

Sequence in context: A151573 A113832 A115631 * A053010 A118452 A286090

Adjacent sequences:  A053005 A053006 A053007 * A053009 A053010 A053011

KEYWORD

easy,nonn,base,changed

AUTHOR

Enoch Haga, Feb 21 2000

EXTENSIONS

Missing terms inserted by Sean A. Irvine, Dec 02 2021

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
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified December 5 04:10 EST 2021. Contains 349530 sequences. (Running on oeis4.)