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A115705 Primes whose digit reversal is a triangular number. 2

%I

%S 3,19,307,523,631,1171,1801,5563,8731,12781,16831,30097,53299,54181,

%T 56629,62011,63667,64063,66457,67411,67807,108127,118801,128413,

%U 130303,131059,160453,188677,192637,196597,300583,302851,357661

%N Primes whose digit reversal is a triangular number.

%H Harvey P. Dale, <a href="/A115705/b115705.txt">Table of n, a(n) for n = 1..400</a>

%e 307 is prime and 703=T(73).

%t Select[Prime[Range[20000]],OddQ[Sqrt[1+8IntegerReverse[#]]]&] (* Requires Mathematica version 10 or later *) (* _Harvey P. Dale_, Jun 01 2019 *)

%Y Cf. A115704.

%K nonn,base

%O 1,1

%A _Giovanni Resta_, Jan 31 2006

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Last modified October 27 16:07 EDT 2021. Contains 348287 sequences. (Running on oeis4.)