OFFSET
1,1
COMMENTS
Equivalently, these are the prime numbers ordered by their reversal. - Rémy Sigrist, Feb 13 2022
LINKS
Rémy Sigrist, Table of n, a(n) for n = 1..9592
EXAMPLE
The last digit of 13 is not '0' and 31 is prime, therefore we append 31.
MATHEMATICA
a = Select[Range[196], IntegerDigits[ # ][[ -1]] != 0 && PrimeQ[FromDigits[Reverse[ IntegerDigits[ # ]]]] &]; b = {}; For[n = 1, n < Length[a] + 1, n++, AppendTo[b, FromDigits[Reverse[IntegerDigits[a[[n]]]]]]]; b
PROG
(PARI) left(str, n) = { my(v, tmp, x); v =""; tmp = Vec(str); ln=length(tmp); if(n > ln, n=ln); for(x=1, n, v=concat(v, tmp[x]); ); return(v) } \\ Get the left n characters from string str
rev(str) = { local(tmp, s, j); tmp = Vec(Str(str)); s=""; forstep(j=length(tmp), 1, -1, s=concat(s, tmp[j])); return(s) } \\ Get the reverse of the input string
rprime(n) = { local(x, y, v); for(x=1, n, y=rev(x); v=Vec(y); if(left(y, 1)<> "0"&&isprime(eval(y)), print1(y", ")) ) }
(Python)
from itertools import count, islice
from sympy import primerange
def A104154_gen(): # generator of terms
yield from (int(d[::-1]) for l in count(1) for d in sorted(str(m)[::-1] for m in primerange(10**(l-1), 10**l)))
CROSSREFS
KEYWORD
AUTHOR
Cino Hilliard, Mar 09 2005
EXTENSIONS
Edited by Stefan Steinerberger, Aug 01 2007
STATUS
approved