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%I #11 Jun 18 2013 15:17:39
%S 2,7,12,37,42,72,217,222,252,432,1297,1302,1332,1512,2592,7777,7782,
%T 7812,7992,9072,15552,46657,46662,46692,46872,47952,54432,93312,
%U 279937,279942,279972,280152,281232,287712,326592,559872,1679617,1679622,1679652,1679832
%N Sums of two powers of 6.
%H T. D. Noe, <a href="/A055257/b055257.txt">Rows n = 0..100 of triangle, flattened</a>
%F a(n) = 6^(n-trinv(n))+6^trinv(n), where trinv(n) = floor((1+sqrt(1+8*n))/2) = A002262(n) and n-trinv(n) = A003056(n)
%F Regarded as a triangle T(n, k) = 6^n + 6^k, so as a sequence a(n) = 6^A002262(n) + 6^A003056(n).
%t t = 6^Range[0, 9]; Select[Union[Flatten[Table[i + j, {i, t}, {j, t}]]], # <= t[[-1]] + 1 &] (* _T. D. Noe_, Oct 09 2011 *)
%Y Cf. A052216.
%K easy,nonn,tabl
%O 0,1
%A _Henry Bottomley_, Jun 22 2000