A338928 Record values of A338565.

1, 2, 3, 4, 7, 17, 21, 38, 58, 82, 148, 174, 176, 360, 362, 479, 846, 1289, 1934, 2196, 3315, 4326, 5701, 8225, 8910, 9507, 11346, 14262, 19832, 25072, 30279, 34638, 46714, 67520, 78082, 82112, 94916, 107902, 175532, 195760, 273164, 275892, 443284, 479324

Offset: 1

Author

Robert Israel, Nov 15 2020

Keywords

• nonn

Crossrefs

Cf. A338565, A338927.

Programs

Maple

ispali:= proc(n) local L;
  L:= convert(n,base,10);
  evalb(L = ListTools:-Reverse(L))
end proc:
N:= 200000: # for terms <= N
Palis:= select(ispali, {$2..N}):
A338565:= Vector(N):
A338565[1]:= 1:
R:= 1: bestv:= 1:
A[1]:= 1:
for n from 2 to N do
  A[n]:=  add(A[n/d], d= numtheory:-divisors(n) intersect Palis);
    if A[n] > bestv then bestv:= A[n]; R:= R, bestv
od:
R;

Mathematica

Block[{a}, a[n_] := If[n == 1, n, Sum[If[(d < n && PalindromeQ[n/d]), a[d], 0], {d, Divisors[n]}]]; Union@ FoldList[Max, Array[a, 10^4]]] (* Michael De Vlieger, Nov 15 2020 *)

Formula

a(n) = A338565(A338927(n)).