Search: id:A057944
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%I A057944
%S A057944 0,1,1,3,3,3,6,6,6,6,10,10,10,10,10,15,15,15,15,15,15,21,21,21,21,21,
%T A057944 21,21,28,28,28,28,28,28,28,28,36,36,36,36,36,36,36,36,36,45,45,45,45,
%U A057944 45,45,45,45,45,45,55,55,55,55,55,55,55,55,55,55,55,66,66,66,66,66,66
%N A057944 Largest triangular number less than or equal to n; write m-th triangular 
               number m+1 times.
%F A057944 a(n) =floor((sqrt(1+8*n)-1)/2)*floor((sqrt(1+8*n)+1)/2)/2 =(trinv(n)*(trinv(n)-1))/
               2 =A000217(A003056(n)) =n-A002262(n)
%e A057944 a(35)=28 since 28 and 36 are successive triangular numbers and 28<=35<36
%Y A057944 Cf. A000217, A003056, A003056, A056944, A057945.
%Y A057944 Sequence in context: A133774 A108581 A073080 this_sequence A080607 A013322 
               A166273
%Y A057944 Adjacent sequences: A057941 A057942 A057943 this_sequence A057945 A057946 
               A057947
%K A057944 easy,nonn
%O A057944 0,4
%A A057944 Henry Bottomley (se16(AT)btinternet.com), Oct 05 2000

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