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 A147804 #12 Aug 12 2020 01:29:00
%S A147804 1,1,100,1,423,28561,3072,124609,119232
%N A147804 Least m coprime to 7 minimizing A007947(m*(7^n-m)).
%C A147804 The minima are given in A147799.
%C A147804 This is related to the abc conjecture: Since m is coprime to 7, it is also coprime to 7^n and thus to 7^n-m. Thus the squarefree kernel A007947(m*(7^n-m)*7^n) = 7*A007947(m(7^n-m)).
%o A147804 (PARI) A147804(n,p=7)={my(b, m=3*n=p^n, t); for(a=1, n\2, a%p || next; m>2*(t=A007947(a)) || next; m>(t*=A007947(n-a)) || next; m=t; b=a); b; }
%Y A147804 Cf. A007947, A147799 (value of minima), A143700, A147802, A147803 (analog for 2^n, 3^n, 5^n), A147300 (analog for any number).
%K A147804 nonn,more
%O A147804 1,3
%A A147804 _M. F. Hasler_, Nov 13 2008
%E A147804 Typo in title corrected by _M. F. Hasler_, Nov 17 2008