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



(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A238850 Right-truncatable reversible primes in base 10. 7
2, 3, 5, 7, 31, 37, 71, 73, 79, 311, 313, 373, 733, 739, 797, 3733 (list; graph; refs; listen; history; text; internal format)



In a general base b, a number qualifies as a member iff: (i) it is a prime, (ii) when its digits in base b are reversed, it is still a prime, and (iii) when, in base b, it has more than one digit and the least significant one is dropped, the remaining prefix has the same properties. This implies that any base-b prefix of such a number (no matter how many right-side digits are truncated, is still a right-truncatable reversible prime. Sequences of this type appear to be all finite (see A238854, A238855, and A238856, used as examples).

This particular sequence is for base b = 10.

See also A238854 for comments on a more general context.


Table of n, a(n) for n=1..16.

Stanislav Sykora, PARI/GP scripts for genetic threads, with code and comments.


739 is a member because it is a prime and so is 937, as well as the pair (73, 37) and 7.


(PARI) See the link.


In base 16: A238851, 100: A238852, 256: A238853.

In base n: A238854 (largest), A238855 (totals), A238856 (maximum digits), A238857 (m-digit counts).

Cf. A007500, A023107, A024770, A237600, A237601, A237602.

Sequence in context: A054797 A297710 A287945 * A245064 A052014 A236255

Adjacent sequences:  A238847 A238848 A238849 * A238851 A238852 A238853




Stanislav Sykora, Mar 06 2014



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 May 7 20:36 EDT 2021. Contains 343652 sequences. (Running on oeis4.)