A072387 - OEIS

%I #20 Nov 27 2021 15:36:23

%S 1,10,190,11026,11476,12880,13366,19306,21115,23005,26335,28441,36046,

%T 53956,54946,58996,60031,65341,68635,70876,72010,83845,91378,1030330,

%U 1047628,1095940,1100386,1154440,1205128,1209790,1223830,1242676,1247410,1266436,1285606

%N Triangular number x such that x + reverse of x is a prime.

%H Amiram Eldar, <a href="/A072387/b072387.txt">Table of n, a(n) for n = 1..10000</a>

%e 10 is a term because it is a triangular number and 10 + 01 = 11 is a prime.

%t tri[n_] := n*(n + 1)/2; tri /@ Select[Range[10^3], PrimeQ[(t = tri[#]) + FromDigits @ Reverse @ IntegerDigits[t]] &] (* _Amiram Eldar_, Aug 24 2020 *)

%t Select[Accumulate[Range[2000]],PrimeQ[#+IntegerReverse[#]]&] (* _Harvey P. Dale_, Nov 27 2021 *)

%o (PARI) isok(n) = ispolygonal(n, 3) && isprime(n+subst(Polrev(digits(n)), x, 10)); \\ _Michel Marcus_, Nov 29 2014

%Y Intersection of A000217 and A072366. - _Michel Marcus_, Nov 29 2014

%Y Cf. A056964.

%K base,nonn

%O 1,2

%A _Shyam Sunder Gupta_, Jul 20 2002

%E More terms from _Michel Marcus_, Nov 29 2014