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A371730 Indices of records in A371729: numbers k with A371729(k) > A371729(m) for all m < k.

%I A371730 #13 Apr 26 2025 20:27:32
%S A371730 2,5,9,13,17,25,37,41,49,73,97,109,161,181,289,307,361,433,529,701,
%T A371730 841,881,961,1189,1369,1681,1849,2209,2393,2449,3277,3457,3781,4096,
%U A371730 4159,4841,4861,5741,5851,6049,7921,10201,11449,11881,15049,15401,19601,27026,32768
%N A371730 Indices of records in A371729: numbers k with A371729(k) > A371729(m) for all m < k.
%C A371730 The corresponding record values are 0, 1, 2, 3, 4, 5, 7, 8, 9, 11, 12, ... (see the link for more values).
%H A371730 Amiram Eldar, <a href="/A371730/b371730.txt">Table of n, a(n) for n = 1..69</a> (terms below 10^6)
%H A371730 Amiram Eldar, <a href="/A371730/a371730.txt">Table of n, a(n), A371729(a(n)) for n = 1..69</a>.
%H A371730 Wikipedia, <a href="http://en.wikipedia.org/wiki/Pseudoprime">Pseudoprime</a>.
%H A371730 <a href="/index/Ps#pseudoprimes">Index entries for sequences related to pseudoprimes</a>.
%t A371730 f[k_] := Count[Range[4, k - 1], _?(CompositeQ[#] && PowerMod[k, # - 1, #] == 1 &)]; seq[kmax_] := Module[{s = {}, fm = -1, f1}, Do[f1 = f[k]; If[f1 > fm, fm = f1; AppendTo[s, k]], {k, 2, kmax}]; s]; seq[2500]
%o A371730 (PARI) f(n) = {my(c=0); forcomposite(k = 4, n-1, if(Mod(n, k)^(k-1) == 1, c++)); c;}
%o A371730 lista(kmax) = {my(fm = -1, f1); for(k = 2, kmax, f1 = f(k); if(f1 > fm, fm = f1; print1(k, ", ")));}
%Y A371730 Cf. A371729.
%K A371730 nonn
%O A371730 1,1
%A A371730 _Amiram Eldar_, Apr 05 2024