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%I #15 Feb 14 2015 17:00:32
%S 1,2,3,7,8,15,32,64,63,224,255,1280,512,3968,6399,10240,4095,14336,
%T 32768,65535,229375,180224,483327,262143,2097151,1048575,14680064,
%U 17432576,33554432,67108864,16777215
%N Indices of triangular numbers listed in A075088.
%C a(32) = 134217728. - _Robert G. Wilson v_, Jun 28 2010
%H Donovan Johnson, <a href="/A076550/b076550.txt">Table of n, a(n) for n = 0..51</a>
%F A000217(a(n)) = A075088(n).
%t f[n_] := Plus @@ Last /@ FactorInteger@n; t = Table[0, {100}]; k = 1; While[k < 10^9/4, a = f[k] + f[k + 1] -1; If[ t[[a + 1]] == 0, t[[a + 1]] = k; Print[{a, k}]]; k++ ]; t (* _Robert G. Wilson v_, Jun 28 2010 *)
%Y Cf. A000217, A075088.
%K nonn
%O 0,2
%A _Shyam Sunder Gupta_, Oct 19 2002
%E Edited by _Ray Chandler_, Dec 17 2004
%E a(26)-a(30) from _Ray Chandler_, Dec 22 2004