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A100970 Integers n that are Rhonda numbers to base 8. 17

%I #16 Jul 10 2021 11:43:24

%S 1836,6318,6622,10530,14500,14739,17655,18550,25398,25956,30562,39215,

%T 39325,50875,51429,52887,55611,56420,58548,59731,60604,72358,74620,

%U 76581,78780,81370,84180,85949,103350,103788,108750,112914,118233

%N Integers n that are Rhonda numbers to base 8.

%C See A099542 for definition of Rhonda numbers and some links.

%H Reinhard Zumkeller, <a href="/A100970/b100970.txt">Table of n, a(n) for n = 1..1000</a>

%H Eric Weisstein's World of Mathematics, <a href="http://mathworld.wolfram.com/RhondaNumber.html">Rhonda Number</a>

%H Wikipedia, <a href="http://www.wikipedia.org/wiki/Octal">Octal</a>

%e Product of base 8 digits of 1836 is 3*4*5*4=240 and sum of prime factors of 1826 is 2*2+3*3+17=30 and 240=8*30.

%t rhda8Q[n_]:=Times@@IntegerDigits[n,8]==8*Total[Times@@@FactorInteger[n]]; Select[Range[120000],rhda8Q] (* _Harvey P. Dale_, Jul 10 2021 *)

%o (Haskell)

%o a100970 n = a100970_list !! (n-1)

%o a100970_list = filter (rhonda 8) a255805_list

%o -- Function rhonda as in A099542.

%o -- _Reinhard Zumkeller_, Mar 08 2015

%Y Cf. Rhonda numbers to other bases: A100968 (base 4), A100969 (base 6), A100973 (base 9), A099542 (base 10), A100971 (base 12), A100972 (base 14), A100974 (base 15), A100975 (base 16), A255735 (base 18), A255732 (base 20), A255736 (base 30), A255731 (base 60), see also A255872.

%Y Cf. A001414, A027746, A007094, subsequence of A255805.

%Y Column k=3 of A291925.

%K easy,nonn,base

%O 1,1

%A Mark Hudson (mrmarkhudson(AT)hotmail.com), Nov 24 2004

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Last modified March 28 08:22 EDT 2024. Contains 371236 sequences. (Running on oeis4.)