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 A354386 #11 May 30 2022 10:30:32 %S A354386 3,2,337,2633,14143,6108437,373777931 %N A354386 a(n) is the first prime that is the start of a sequence of exactly n primes under the map p -> p + A001414(p-1) + A001414(p+1). %e A354386 a(3) = 337 because 337, 337+A001414(336)+A001414(338) = 383, and 383+A001414(382)+A001414(384) = 593 are prime, but 593+A001414(592)+A001414(594) = 660 is not prime, and 337 is the first prime for which this works. %p A354386 spf:= proc(n) option remember; local t; add(t[1]*t[2], t=ifactors(n)[2]) end proc: %p A354386 f:= n -> spf(n-1)+n+spf(n+1): %p A354386 g:= proc(n) option remember; %p A354386 if not isprime(n) then return 0 fi; %p A354386 1 + procname(f(n)) %p A354386 end proc: %p A354386 V:= Vector(7): count:= 0: %p A354386 p:= 1: %p A354386 while count < 7 do %p A354386 p:= nextprime(p); %p A354386 v:= g(p); %p A354386 if V[v] = 0 then V[v]:= p; count:= count+1 fi; %p A354386 od: %p A354386 convert(V,list); %t A354386 f[1] = 0; f[n_] := Plus @@ Times @@@ FactorInteger[n]; g[n_] := -1 + Length @ NestWhileList[# + f[# - 1] + f[# + 1] &, n, PrimeQ]; seq[len_, max_] := Module[{s = Table[0, {len}], c = 0, p = 1, i}, While[p < max && c < len, p = NextPrime[p]; i = g[p]; If[i <= len && s[[i]] == 0, c++; s[[i]] = p]]; s]; seq[6, 10^7] (* _Amiram Eldar_, May 29 2022 *) %o A354386 (Python) %o A354386 from sympy import factorint, isprime, nextprime %o A354386 def A001414(n): return sum(p*e for p, e in factorint(n).items()) %o A354386 def f(p): return p + A001414(p-1) + A001414(p+1) %o A354386 def a(n): %o A354386 p, count = 1, 0 %o A354386 while count != n: %o A354386 p = nextprime(p) %o A354386 fp, count = f(p), 1 %o A354386 while isprime(fp): fp = f(fp); count += 1 %o A354386 return p %o A354386 print([a(n) for n in range(1, 6)]) # _Michael S. Branicky_, May 29 2022 %Y A354386 Cf. A001414, A127305. %K A354386 nonn,more %O A354386 1,1 %A A354386 _J. M. Bergot_ and _Robert Israel_, May 24 2022