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 A212016 Sums of the squares of two or more consecutive integers. 5

%I

%S 1,2,5,6,10,13,14,15,19,25,28,29,30,31,35,41,44,50,54,55,56,60,61,69,

%T 77,85,86,90,91,92,96,105,110,113,121,126,135,139,140,141,145,146,149,

%U 154,170,174,181,182,190,194,195,199,203,204,205,209,218

%N Sums of the squares of two or more consecutive integers.

%C Subsequence of A062861.

%C Contains A212015 as a subsequence.

%C A174069 is a subsequence. - _Altug Alkan_, Dec 24 2015

%H Robert Israel, <a href="/A212016/b212016.txt">Table of n, a(n) for n = 1..10000</a>

%p N:= 1000: # to get all terms <=N

%p g:= x -> x*(x+1)*(2*x+1)/6:

%p S:= select(`<=`,{seq(seq(g(b)-g(a), a= -b-1 .. b-2), b = 1..floor((sqrt(2*N-1)+1)/2))},N):

%p sort(convert(S,list)); # _Robert Israel_, Jan 05 2016

%o (PARI) { isA212016(t) = fordiv(6*t,k, if(k==1,next); z=(k^2-1)/3; if(issquare(4*t/k-z), return(k)); if(z>4*t/k,break); ); 0 }

%Y Cf. A062861, A174069, A212015.

%K nonn,easy

%O 1,2

%A _Max Alekseyev_, Apr 26 2012

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Last modified August 18 04:50 EDT 2019. Contains 326072 sequences. (Running on oeis4.)