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

1, 2, 5, 6, 10, 13, 14, 15, 19, 25, 28, 29, 30, 31, 35, 41, 44, 50, 54, 55, 56, 60, 61, 69, 77, 85, 86, 90, 91, 92, 96, 105, 110, 113, 121, 126, 135, 139, 140, 141, 145, 146, 149, 154, 170, 174, 181, 182, 190, 194, 195, 199, 203, 204, 205, 209, 218

Offset

1,2

Comments

Subsequence of A062861.

Contains A212015 as a subsequence.

A174069 is a subsequence. - Altug Alkan, Dec 24 2015

Links

Robert Israel, Table of n, a(n) for n = 1..10000

Maple

N:= 1000: # to get all terms <=N
g:= x -> x*(x+1)*(2*x+1)/6:
S:= select(`<=`, {seq(seq(g(b)-g(a), a= -b-1 .. b-2), b = 1..floor((sqrt(2*N-1)+1)/2))}, N):
sort(convert(S, list)); # Robert Israel, Jan 05 2016

Prog

(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 }

Crossrefs

Cf. A062861, A174069, A212015.

Sequence in context: A187902 A187231 A162340 * A212015 A255341 A089269

Adjacent sequences: A212013 A212014 A212015 * A212017 A212018 A212019

Keyword

nonn,easy

Author

Max Alekseyev, Apr 26 2012

Status

approved