A147801 Minimal value of A007947(m*(3^n-m)) with m coprime to 3.

2, 2, 10, 10, 22, 110, 278, 238, 1054, 1342, 11066, 6118, 18734, 107030, 557270, 163030, 1440430, 2195110, 11016290, 3641210, 23250370, 38188766

Offset

1,1

Comments

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

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, ...

Links

Table of n, a(n) for n=1..22.

Prog

(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; }

Crossrefs

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

Sequence in context: A249152 A216708 A032005 * A367545 A263053 A361835

Adjacent sequences: A147798 A147799 A147800 * A147802 A147803 A147804

Keyword

nonn,more

Author

M. F. Hasler, Nov 13 2008

Extensions

a(17)-a(22) from Jinyuan Wang, Aug 11 2020

Status

approved