cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

A358693 Numbers k such that k / (sum of digits of k) is the square of a prime.

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%I A358693 #63 Jan 12 2023 19:25:49
%S A358693 12,24,36,48,81,150,225,375,441,735,882,1014,1452,1521,1815,2023,2028,
%T A358693 2178,2312,2535,2601,3549,3610,4046,4332,4335,4624,4913,5054,5415,
%U A358693 5491,5780,6069,6137,6358,6647,6936,7581,7942,8664,8959,9386,9522,9747,10092,11532,12321,12615,12696
%N A358693 Numbers k such that k / (sum of digits of k) is the square of a prime.
%C A358693 Terms k from A001102 such that k / (sum of digits of k) is the square of a prime.
%t A358693 Select[Range[13000], PrimeQ[Sqrt[#/Plus @@ IntegerDigits[#]]] &] (* _Amiram Eldar_, Jan 01 2023 *)
%o A358693 (PARI) isok(k) = my(r); issquare(k/sumdigits(k), &r) && (denominator(r)==1) && isprime(r); \\ _Michel Marcus_, Jan 01 2023
%Y A358693 Cf. A001102, A001248, A007953.
%K A358693 nonn,base
%O A358693 1,1
%A A358693 _Andi Fugard_, Jan 01 2023
%E A358693 More terms from _Michel Marcus_, Jan 01 2023