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.
%I A090194 #12 May 21 2024 16:37:52 %S A090194 2,43,61,263,433,461,601,641,653,661,821,857,1061,1063,1187,1361,1423, %T A090194 1487,1613,1811,1871,1877,2063,2081,2143,2161,2621,2801,2837,3061, %U A090194 3163,3581,3623,3631,3643,3851,4561,5087,5261,5381,5623,5807,5861,6011,6053 %N A090194 Primes which when multiplied by their largest digit and 1 is added form another prime. %H A090194 Harvey P. Dale, <a href="/A090194/b090194.txt">Table of n, a(n) for n = 1..1000</a> %F A090194 In the prime sequence, select largest digit in each prime, multiply by the prime containing that digit, then add 1. If the result is another prime, add to sequence. %e A090194 a(2)=43. Largest digit is 4. Multiply 43*4=172. 172+1=173, prime. %t A090194 Select[Prime[Range[1000]],PrimeQ[1+#*Max[IntegerDigits[#]]]&] (* _Harvey P. Dale_, May 21 2024 *) %o A090194 (PARI) isok(p) = isprime(p) && isprime(p*vecmax(digits(p))+1); \\ _Michel Marcus_, Jun 08 2014 %Y A090194 Cf. A060418. %K A090194 easy,nonn,base %O A090194 1,1 %A A090194 _Enoch Haga_, Jan 22 2004