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%I #16 Mar 23 2023 07:52:22
%S 0,2,6,4,18,7,12,30,9,48,11,60,36,14,78,16,90,19,24,102,21,120,23,132,
%T 108,26,150,28,162,31,42,174,33,192,35,204,72,38,222,40,234,43,180,
%U 246,45,264,47,276,54,50,294,52,306,55,288,318,57,336,59,348,66,62,366,64
%N Earliest sequence with a(a(n)) = 6n.
%H T. D. Noe, <a href="/A054786/b054786.txt">Table of n, a(n) for n = 0..1000</a>
%H <a href="/index/Aa#aan">Index entries for sequences of the a(a(n)) = 2n family</a>
%F a(12n)=6*a(2n), a(12n+1)=12n+2, a(12n+2)=72n+6, a(12n+3)=12n+4, a(12n+4)=72n+18, a(12n+5)=12n+7, a(12n+6)=6*a(2n+1), a(12n+7)=72n+30, a(12n+8)=12n+9, a(12n+9)=72n+48, a(12n+10)=12n+11, a(12n+11)=72n+60.
%t a[0] = 0; a[n_] := a[n] = Switch[ Mod[n, 12], 0 | 6, 6*a[n/6], 1 | 3 | 8 | 10, n+1, 2 | 4 | 9 | 11, 6*n-6, 5, n+2, 7, 6*n-12]; Table[a[n], {n, 0, 63}] (* _Jean-François Alcover_, Dec 20 2011, after formula *)
%Y Cf. A002516, A002517, A002518, A007379.
%K nice,nonn
%O 0,2
%A _Henry Bottomley_, Apr 27 2000
%E Typo in formula corrected by _Reinhard Zumkeller_, Jul 23 2010
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