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 1-7 of 7 results.

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

Original entry on oeis.org

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

Views

Author

Max Alekseyev, Apr 26 2012

Keywords

Comments

Subsequence of A062861.
Contains A212015 as a subsequence.
A174069 is a subsequence. - Altug Alkan, Dec 24 2015

Crossrefs

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 }

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 *)

A062862 Number of ways n can be written as the sum of squares of consecutive numbers (possibly including squares of negative numbers).

Original entry on oeis.org

1, 4, 1, 0, 2, 4, 2, 0, 0, 2, 1, 0, 0, 2, 4, 2, 2, 0, 0, 2, 0, 0, 0, 0, 0, 4, 0, 0, 1, 2, 4, 2, 0, 0, 0, 2, 2, 0, 0, 0, 0, 2, 0, 0, 2, 0, 0, 0, 0, 2, 2, 0, 0, 0, 2, 4, 2, 0, 0, 0, 3, 2, 0, 0, 2, 0, 0, 0, 0, 2, 0, 0, 0, 0, 0, 0, 0, 2, 0, 0, 0, 2, 0, 0, 0, 4, 2, 0, 0, 0, 2, 4, 2, 0, 0, 0, 2, 0, 0, 0, 2, 0, 0, 0, 0
Offset: 0

Views

Author

Henry Bottomley, Jun 25 2001

Keywords

Examples

			a(25)=4 since 25 = 5^2 = 3^2+4^2 = (-4)^2+(-3)^2 = (-5)^2.
		

Crossrefs

If a(n) is zero then n is in A062863, otherwise in A062861. If a(n) is odd then n is in A006331.

A062863 Numbers which cannot be written as sums of squares of consecutive numbers (even allowing squares of negative numbers).

Original entry on oeis.org

3, 7, 8, 11, 12, 17, 18, 20, 21, 22, 23, 24, 26, 27, 32, 33, 34, 37, 38, 39, 40, 42, 43, 45, 46, 47, 48, 51, 52, 53, 57, 58, 59, 62, 63, 65, 66, 67, 68, 70, 71, 72, 73, 74, 75, 76, 78, 79, 80, 82, 83, 84, 87, 88, 89, 93, 94, 95, 97, 98, 99, 101, 102, 103, 104, 106, 107, 108
Offset: 0

Views

Author

Henry Bottomley, Jun 25 2001

Keywords

Crossrefs

Complement of A062861. Cf. A062862.

Programs

  • Mathematica
    Complement[Range[150],Union[Flatten[Table[Union[Total/@(Partition[ Range[-50,50],i,1]^2)],{i,20}]]]] (* Harvey P. Dale, Jan 04 2012 *)

A212017 Integers n such that n^3 is the sum of consecutive integer squares.

Original entry on oeis.org

0, 1, 4, 9, 11, 16, 25, 26, 36, 47, 49, 64, 65, 66, 81, 100, 109, 121, 144, 169, 196, 225, 256, 289, 324, 361, 400, 441, 484, 529, 576, 625, 676, 729, 784, 841, 900, 921, 935, 961, 1024, 1079, 1089, 1156, 1225, 1296, 1369, 1444, 1521, 1600
Offset: 1

Views

Author

Max Alekseyev, Apr 26 2012

Keywords

Comments

Integers n such that n^3 belongs to A062861.

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 1-7 of 7 results.