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A104301 Primes which are the reverse concatenation of two consecutive square numbers.

%I A104301 #20 Jul 15 2025 03:58:23
%S A104301 41,6449,196169,576529,11561089,14441369,27042601,38443721,51845041,
%T A104301 60845929,67246561,84648281,1081610609,2073620449,2190421609,
%U A104301 2822427889,3240032041,4000039601,4326442849,5017649729,5290052441,6250062001,7507674529,8294482369,103684103041
%N A104301 Primes which are the reverse concatenation of two consecutive square numbers.
%H A104301 Amiram Eldar, <a href="/A104301/b104301.txt">Table of n, a(n) for n = 1..10000</a>
%e A104301 The first term is 41 which is a prime and is the reverse concatenation of 1 and 4 which are two consecutive square numbers.
%t A104301 cat[s_] := FromDigits[Flatten[IntegerDigits[s]]]; Select[cat /@ Reverse /@ Partition[Range[350]^2, 2, 1], PrimeQ] (* _Amiram Eldar_, Jul 15 2025 *)
%o A104301 (Python)
%o A104301 from sympy import isprime
%o A104301 A104301_list = []
%o A104301 for n in range(1, 2000):
%o A104301     x = int(str((n+1)**2)+str(n**2))
%o A104301     if isprime(x):
%o A104301         A104301_list.append(x) # _Chai Wah Wu_, Sep 13 2014
%Y A104301 These are the primes in A246972.
%Y A104301 Cf. A104242, A104302, A104303, A104304.
%K A104301 base,nonn
%O A104301 1,1
%A A104301 _Shyam Sunder Gupta_, Apr 17 2005