%I #17 Jun 05 2022 08:30:51

%S 1,3,14,15,25,38,61,121,288,1427,3201,3532,4514,18824,56506,138299,

%T 160019,175672,389021,792425,1307363,2484543,5810361,6570899,18661982,

%U 28689761,54425951,120552563,145950769,1046047048,11369776859,12564976008,19468787723,36754001297

%N Indices of records in A218344.

%C The corresponding composite numbers A002808(a(n)) are 4, 8, 24, 25, 38, 55, 85, ... (see the link for more values).

%H Amiram Eldar, <a href="/A354740/a354740_1.txt">Table of n, a(n), A218345(n), A002808(a(n)) for n = 1..34</a>

%F A218344(a(n)) = A218345(n).

%t comp = Select[Range[10^6], CompositeQ]; f[n_] := Module[{k = 1}, While[! PrimeQ[k*n + 1], k++]; k]; vs = f /@ comp; m = 0; s = {}; Do[v = vs[[k]]; If[v > m, m = v; AppendTo[s, k]], {k, 1, Length[vs]}]; s

%Y Cf. A002808, A218344, A218345.

%K nonn

%O 1,2

%A _Amiram Eldar_, Jun 05 2022