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 A119487 #18 Sep 08 2022 08:45:25 %S A119487 43,83,197,271,359,631,977,1307,1553,2371,2693,2953,3271,4561,5051, %T A119487 5407,6551,8713,9941,10651,22573,23333,27689,31051,33203,34123,37507, %U A119487 52639,60919,64399,79279,82699,93559,112061,119131,136033,146921,197959 %N A119487 Primes of the form i*prime(i) + (i+1)*prime(i+1). %C A119487 Primes in A152117; also called linking primes, cf. A152658. - _Klaus Brockhaus_, Dec 11 2008 %H A119487 Klaus Brockhaus, <a href="/A119487/b119487.txt">Table of n, a(n) for n=1..10000</a> %e A119487 The third prime is 5 and the fourth is 7. Therefore 5*3 + 7*4 = 15 + 28 = 43 which is a prime. %p A119487 P:=proc(n) local i,j; for i from 1 by 1 to n do j:=ithprime(i)*i +ithprime(i+1)*(i+1); if isprime(j) then print(i); fi; od; end: P(200); %o A119487 (Magma) [ q: n in [1..133] | IsPrime(q) where q is n*p+(n+1)*NextPrime(p) where p is NthPrime(n) ] // _Klaus Brockhaus_, Dec 11 2008 %Y A119487 Cf. A119488. %Y A119487 Cf. A152117 (n*(n-th prime) + (n+1)*((n+1)-th prime)), A152658 (beginnings of maximal chains of primes). - _Klaus Brockhaus_, Dec 11 2008 %K A119487 easy,nonn %O A119487 1,1 %A A119487 _Paolo P. Lava_ and _Giorgio Balzarotti_, May 23 2006