%I A077003
%S A077003 1,1,1,2,4,9,22,59,167,501,1585,5258,18215,65676,245738,951740,3806961,
%T A077003 15696503,66594623,290279233,1298168196,5948954024,27903067710,
%U A077003 133818411722,655573653819,3277868269096,16713914267109,86848046111951
%N A077003 a(n)= index of triangular number A077002(n).
%p A077003 a[1] := 1:b[1] := 1:for n from 2 to 100 do a[n] := floor(evalf(-1/2+1/
               2*sqrt(1+8*(n-1)*a[n-1])+1/10^50,300)):b[n] := a[n]:a[n] := a[n]*(a[n]+1)/
               2:od:seq(b[l],l=1..100);
%Y A077003 Cf. A077002.
%Y A077003 Sequence in context: A092920 A035053 A000571 this_sequence A046917 A159329 
               A159334
%Y A077003 Adjacent sequences: A077000 A077001 A077002 this_sequence A077004 A077005 
               A077006
%K A077003 nonn
%O A077003 1,4
%A A077003 Amarnath Murthy (amarnath_murthy(AT)yahoo.com), Oct 26 2002
%E A077003 More terms from Sascha Kurz (sascha.kurz(AT)uni-bayreuth.de), Jan 26 
               2003