OFFSET
1,1
COMMENTS
No other solutions below 2*10^9 (probably finite). - Dec 15 1999
No other solutions below 10^20. - David A. Corneth, Oct 28 2023, recomputed after a remark from Max Alekseyev, David A. Corneth, Aug 20 2024
Primes p such that p^2 is in A062826. - Max Alekseyev, Aug 18 2024
LINKS
David A. Corneth, PARI program
EXAMPLE
From David A. Corneth, Oct 28 2023: (Start)
31 is in the sequence as 31 is prime and 31^2 = 961 which has its digits in nonascending order.
2979 is not in the sequence even though 2979^2 = 8874441 does have digits in nonascending order but 2979 = 3^2 * 331 is not prime. (End)
PROG
(PARI) is(n) = my(d = digits(n^2)); d == vecsort(d, , 4) && isprime(n) \\ David A. Corneth, Oct 28 2023
(PARI) \\ see link for a faster program
CROSSREFS
KEYWORD
nonn,base,hard,more
AUTHOR
EXTENSIONS
Name clarified by Jon E. Schoenfield, Oct 27 2023
STATUS
approved