|
%I #13 Jun 13 2021 08:25:03
%S 2,5,71,73,101,109,263,269,523,541,587,1061,1063,2089,2251,2273,2297,
%T 2843,2861,5441,5477,5483,6203,6221,7129,7507,7937,10009,10163,10169,
%U 10487,10691,20201,20693,22391,22769,24023,24877,26141,26171,26723
%N Primes whose reversal - 1 is a square.
%C The first digit of a(n) cannot be 3, 4, 8 or 9. - _Altug Alkan_, Dec 20 2015
%H Chai Wah Wu, <a href="/A167218/b167218.txt">Table of n, a(n) for n = 1..7256</a>
%e 71 is prime and 17-1 = 16 = 4^2.
%o (Python)
%o from sympy import isprime
%o A167218_list, i, j = [], 0, 1
%o while j < 10**10:
%o p = int(str(j)[::-1])
%o if j % 10 and isprime(p):
%o A167218_list.append(p)
%o j += 2*i+1
%o i += 1
%o A167218_list = sorted(A167218_list) # _Chai Wah Wu_, Dec 20 2015
%o (PARI) lista(nn) = {forprime(p=2, nn, if (issquare(eval(concat(Vecrev(Str(p))))-1), print1(p, ", ")););} \\ _Michel Marcus_, Dec 20 2015
%Y Cf. A007488.
%K base,nonn
%O 1,1
%A _Claudio Meller_, Oct 30 2009
|
