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A338927 Locations of records in A338565.

%I A338927 #10 Nov 15 2020 22:33:58
%S A338927 1,4,6,8,12,24,36,48,72,96,144,192,240,288,384,432,576,864,1152,1440,
%T A338927 1728,2304,2880,3456,4320,4608,5184,5760,6912,8640,10368,11520,13824,
%U A338927 17280,20736,23040,25920,27648,34560,41472,51840,62208,69120,82944
%N A338927 Locations of records in A338565.
%C A338927 The first term divisible by 3 is a(3)=6.
%C A338927 The first term divisible by 5 is a(13)=240.
%C A338927 The first term divisible by 11 is a(48)=190080.
%e A338927 a(3) = 6 is in the sequence because A338565(6) = 3 is greater than A338565(n) for n < 6.
%p A338927 ispali:= proc(n) local L;
%p A338927   L:= convert(n,base,10);
%p A338927   evalb(L = ListTools:-Reverse(L))
%p A338927 end proc:
%p A338927 N:= 200000: # for terms <= N
%p A338927 Palis:= select(ispali, {$2..N}):
%p A338927 A338565:= Vector(N):
%p A338927 A338565[1]:= 1:
%p A338927 R:= 1: bestv:= 1:
%p A338927 A[1]:= 1:
%p A338927 for n from 2 to N do
%p A338927   A[n]:=  add(A[n/d], d= numtheory:-divisors(n) intersect Palis);
%p A338927     if A[n] > bestv then bestv:= A[n]; R:= R, n
%p A338927 od:
%p A338927 R;
%t A338927 Block[{a, s}, a[n_] := If[n == 1, n, Sum[If[(d < n && PalindromeQ[n/d]), a[d], 0], {d, Divisors[n]}]]; s = Array[a, 10^4]; Map[FirstPosition[s, #][[1]] &, Union@ FoldList[Max, s]] ] (* _Michael De Vlieger_, Nov 15 2020 *)
%Y A338927 Cf. A338565, A328928.
%K A338927 nonn
%O A338927 1,2
%A A338927 _Robert Israel_, Nov 15 2020