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A265211 Squares that become prime when their rightmost digit is removed.

%I A265211 #14 Sep 08 2022 08:46:14
%S A265211 25,36,196,676,1936,2116,3136,4096,5476,5776,7396,8836,11236,21316,
%T A265211 23716,26896,42436,51076,55696,59536,64516,65536,75076,81796,87616,
%U A265211 92416,98596,106276,118336,119716,132496,179776,190096,198916,206116,215296,256036,274576,287296
%N A265211 Squares that become prime when their rightmost digit is removed.
%C A265211 All the terms in this sequence, except a(1) end in digit 6.
%C A265211 All the terms except a(2) are congruent to 1 (mod 3).
%C A265211 All terms except a(1) are of the form 10*p+6 where p is a prime of the form 10*x^2 + 8*x + 1 or 10*x^2 + 12*x + 3. The Bunyakovsky conjecture implies that there are infinitely many of both of these types. - _Robert Israel_, Jan 12 2016
%H A265211 K. D. Bajpai, <a href="/A265211/b265211.txt">Table of n, a(n) for n = 1..10000</a>
%H A265211 Wikipedia, <a href="https://en.wikipedia.org/wiki/Bunyakovsky_conjecture">Bunyakovsky conjecture</a>.
%e A265211 196 = 14^2 becomes the prime 19 when its rightmost digit is removed.
%e A265211 3136 = 56^2 becomes the prime 313 when its rightmost digit is removed.
%p A265211 select(t -> isprime(floor(t/10)), [seq(i^2, i=1..1000)]); # _Robert Israel_, Jan 12 2016
%t A265211 A265211 = {}; Do[k = n^2; If[PrimeQ[Floor[k/10]], AppendTo[A265211 , k]], {n, 1500}]; A265211
%t A265211 Select[Range[540]^2,PrimeQ[FromDigits[Most[IntegerDigits[#]]]]&] (* _Harvey P. Dale_, Aug 02 2016 *)
%o A265211 (PARI) for(n=1,1000, k=n^2; if(isprime(k\10), print1(k, ", ")));
%o A265211 (Magma) [k: n in [1..100] | IsPrime(Floor(k/10)) where k is n^2];
%Y A265211 Cf. A000290, A225873, A225885, A226354, A226531.
%K A265211 nonn,base,easy
%O A265211 1,1
%A A265211 _K. D. Bajpai_, Dec 05 2015