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 A278968 #8 Jan 25 2024 07:54:50 %S A278968 1,1,1,1,3,5,1,27,3,565,1,7085,25,3,11,1266205,9099507,17602325, %T A278968 128207979,119,1,13 %N A278968 Least number k such that pk is of minimal Hamming weight, where p is the n-th prime. %o A278968 (PARI) min1s(p)=my(o=znorder(Mod(2,p)), v1=Set(powers(Mod(2,p),o)), v=v1, s=1); while(!setsearch(v,Mod(0,p)), v=setbinop((x,y)->x+y,v,v1); s++); s %o A278968 a(n,p=prime(n))=my(m=min1s(p),t=p,k=2*p); while(hammingweight(t)>m, t+=k); t/p %Y A278968 Cf. A278966, A278967, A086342. %K A278968 nonn,more %O A278968 1,5 %A A278968 _Charles R Greathouse IV_, Dec 02 2016