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

Author

Max Alekseyev, Apr 26 2012

Keywords

• nonn
• easy

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

Crossrefs

Cf. A062861, A174069, A212015.

Programs

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

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 }