cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

Showing 1-4 of 4 results.

A174069 Numbers that can be written as a sum of at least 2 squares of consecutive positive integers.

Original entry on oeis.org

5, 13, 14, 25, 29, 30, 41, 50, 54, 55, 61, 77, 85, 86, 90, 91, 110, 113, 126, 135, 139, 140, 145, 149, 174, 181, 190, 194, 199, 203, 204, 221, 230, 245, 255, 265, 271, 280, 284, 285, 294, 302, 313, 330, 355, 365, 366, 371, 380, 384, 385, 415, 421, 434, 446, 451
Offset: 1

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Author

Keywords

Comments

Numbers are listed without multiplicity: 365 is the first term that is the sum of two or more squares in more than one way. See A062681 for other numbers of that form. - M. F. Hasler, Dec 22 2013
A subsequence of A212016. This sequence focuses on the squares of consecutive positive integers. - Altug Alkan, Dec 24 2015

Examples

			5 = 1^2 + 2^2
13 = 2^2 + 3^2
14 = 1^2 + 2^2 + 3^2
25 = 3^2 + 4^2
		

Crossrefs

Cf. A111774, A138591, A151557 (subset of squares), A163251 (subset of primes).
See also A062681, A212016.

Programs

  • Mathematica
    max = 50^2; lst = {}; Do[z = n^2; Do[z += (n + x)^2; If[z > max, Break[]]; AppendTo[lst, z], {x, max/2}], {n, max/2}]; Union[lst]
  • PARI
    N=20;a=[];for(i=2,N, for(k=1,i-1,if(N^2*2>t=sum(j=i-k,i,j^2),a=setunion(a,Set(t)),break)));a \\ M. F. Hasler, Dec 22 2013

Extensions

Name edited by Altug Alkan, Dec 24 2015

A212015 Nonsquare positive integers that are sums of consecutive integer squares.

Original entry on oeis.org

2, 5, 6, 10, 13, 14, 15, 19, 28, 29, 30, 31, 35, 41, 44, 50, 54, 55, 56, 60, 61, 69, 77, 85, 86, 90, 91, 92, 96, 105, 110, 113, 126, 135, 139, 140, 141, 145, 146, 149, 154, 170, 174, 181, 182, 190, 194, 195, 199, 203, 204, 205, 209, 218, 221, 230, 231
Offset: 1

Views

Author

Max Alekseyev, Apr 26 2012

Keywords

Comments

Nonsquare terms of A062861.
Subsequence of A212016.

Crossrefs

Programs

  • Maple
    filter:= proc(n)
      not issqr(n) and
      ormap(k -> issqr(-3*k^4+3*k^2+36*k*n) and  ((3*k-3*k^2+sqrt(-3*k^4+3*k^2+36*k*n))/(6*k))::integer,
        numtheory:-divisors(6*n))
    end proc:
    select(filter, [$1..1000]); # Robert Israel, Jan 22 2017
  • Mathematica
    filterQ[n_] := !IntegerQ[Sqrt[n]] && AnyTrue[Divisors[6n], IntegerQ[Sqrt[-3 #^4 + 3 #^2 + 36 # n]] && IntegerQ[(3 # - 3 #^2 + Sqrt[-3 #^4 + 3 #^2 + 36 # n])/(6#)]&];
    Select[Range[1000], filterQ] (* Jean-François Alcover, Jun 08 2020, after Maple *)

A212018 Integers m such that m^3 is the sum of two or more consecutive integer squares.

Original entry on oeis.org

1, 11, 26, 47, 65, 66, 109, 921, 935, 1079, 2161, 2820, 2860, 5029, 9105, 10681, 12284, 13156, 16761, 18340, 41921, 43500, 61721, 63765, 64605, 66317, 75130, 99359, 105731, 116180, 122009, 146821, 159371, 218205, 253393, 260165, 264680, 269588, 314919, 403130, 404326, 420365
Offset: 1

Views

Author

Max Alekseyev, Apr 26 2012

Keywords

Comments

Integers m such that m^3 belongs to A212016.
Are there any squares besides 1 in this sequence?

Crossrefs

Subsequence of A212017.

Extensions

a(39)-a(42) from Xianwen Wang, May 23 2025

A182379 Positive integers n such that n^2 is the sum of two or more consecutive integer squares.

Original entry on oeis.org

1, 5, 11, 29, 34, 38, 39, 50, 55, 70, 77, 88, 92, 94, 105, 106, 115, 135, 138, 143, 155, 158, 169, 182, 185, 189, 195, 242, 245, 253, 274, 284, 316, 321, 332, 356, 357, 385, 413, 430, 440, 495, 511, 531, 650, 652, 655, 671, 676, 679, 724, 726, 764
Offset: 1

Views

Author

Max Alekseyev, Apr 26 2012

Keywords

Comments

Integers n such that n^2 belongs to A212016.
{ a(n)^2 : n=1,2,... } forms the set difference of A212016 and A212015.

Crossrefs

Showing 1-4 of 4 results.