A147801 - OEIS

%I #12 Aug 12 2020 08:51:52

%S 2,2,10,10,22,110,278,238,1054,1342,11066,6118,18734,107030,557270,

%T 163030,1440430,2195110,11016290,3641210,23250370,38188766

%N Minimal value of A007947(m*(3^n-m)) with m coprime to 3.

%C Related to the abc conjecture. The minima are reached for m values given in A147802.

%C All terms of this sequence are even, so one could also consider A147801/2 = 1, 1, 5, 5, 11, 55, 139, 119, 527, 671, 5533, 3059, 9367, 53515, 278635, 81515, ...

%o (PARI) A147801(n, p=3) = {my(m=n=p^n); for(x=1, (n-1)\2, x%p || next; A007947(n-x)*A007947(x)<m || next; m=A007947((n-x)*x)); m; }

%Y Cf. A007947, A147298 (general case), A143702 (analog for 2^n), A147800 (analog for 5^n), A147802.

%K nonn,more

%O 1,1

%A _M. F. Hasler_, Nov 13 2008

%E a(17)-a(22) from _Jinyuan Wang_, Aug 11 2020