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A255732 Rhonda numbers in vigesimal number system.

%I A255732 #13 Feb 16 2025 08:33:25
%S A255732 1815,11050,15295,21165,22165,30702,34510,34645,42292,44165,52059,
%T A255732 53416,65945,78430,80712,84251,84835,86591,112608,146055,148144,
%U A255732 156284,175419,178350,194590,200655,201825,202664,204085,209095,209550,211250,212346,212850
%N A255732 Rhonda numbers in vigesimal number system.
%C A255732 See A099542 for definition of Rhonda numbers and for more links.
%H A255732 Reinhard Zumkeller, <a href="/A255732/b255732.txt">Table of n, a(n) for n = 1..1000</a>
%H A255732 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/RhondaNumber.html">Rhonda Number</a>
%H A255732 Wikipedia, <a href="http://www.wikipedia.org/wiki/Vigesimal">Vigesimal</a>
%e A255732 a(1) = 1815 = 4*20^2 + 10*20^1 + 15*20^0 = 3*5*11*11,
%e A255732 with 4 * 10 * 15 = 20 * (3+5+11+11) = 600;
%e A255732 a(10) = 44165 = 5*20^3 + 10*20^2 + 8*20^1 + 5*20^0 = 5*11*11*73,
%e A255732 with 5 * 10 * 8 * 5 = 20 * (5+11+11+73) = 2000.
%o A255732 (Haskell)
%o A255732 a255732 n = a255732_list !! (n-1)
%o A255732 a255732_list = filter (rhonda 20) $ iterate z 1 where
%o A255732    z x = 1 + if r < 29 then x else 30 * z x' where (x', r) = divMod x 30
%o A255732 -- Function rhonda as in A099542.
%Y A255732 Cf. Rhonda numbers to other bases: A100968 (base 4), A100969 (base 6), A100970 (base 8), A100973 (base 9), A099542 (base 10), A100971 (base 12), A100972 (base 14), A100974 (base 15), A100975 (base 16), A255735 (base 18), A255736 (base 30), A255731 (base 60), see also A255872.
%Y A255732 Cf. A001414, A027746.
%Y A255732 Column k=11 of A291925.
%K A255732 nonn,base
%O A255732 1,1
%A A255732 _Reinhard Zumkeller_, Mar 05 2015