%I A061353
%S A061353 1,3,4,0,1,1,2,6,7,5,6,8,9,5,6,6,7,1,2,0,1,3,4,0,1,1,2,6,7,5,6,8,9,5,6,
%T A061353 6,7,1,2,0,1,3,4,0,1,1,2,6,7,5,6,8,9,5,6,6,7,1,2,0,1,3,4,0,1,1,2,6,7,5,
%U A061353 6,8,9,5,6,6,7,1,2,0,1,3,4,0,1,1,2,6,7,5,6,8,9,5,6,6,7,1,2,0,1,3,4,0,1
%N A061353 First column of array shown in A061352.
%C A061353 Least significant digit of the n-th triangular number if n is even.
%F A061353 a(1)=1; if n even, a(n+1)=(a(n)+1) mod 10; if n odd, a(n+1)=(a(n)+2n) 
               mod 10.
%F A061353 a(2n-1) = n*(2n-1)- 10*Floor[n*(2n-1)/10] +1, a(2n) = n(2n+1)- 10*Floor[n*(2n+1)/
               10].
%Y A061353 Sequence in context: A131099 A098800 A087666 this_sequence A016653 A096088 
               A107681
%Y A061353 Adjacent sequences: A061350 A061351 A061352 this_sequence A061354 A061355 
               A061356
%K A061353 nonn,easy
%O A061353 1,2
%A A061353 Amarnath_murthy (amarnath_murthy(AT)yahoo.com), Apr 28 2001
%E A061353 More terms and formula from Larry Reeves (larryr(AT)acm.org), May 15 
               2001