A292313 Numbers that are the sum of three squares in arithmetic progression.

75, 300, 507, 675, 867, 1200, 1875, 2028, 2523, 2700, 3468, 3675, 4107, 4563, 4800, 5043, 6075, 7500, 7803, 8112, 8427, 9075, 10092, 10800, 11163, 12675, 13872, 14700, 15987, 16428, 16875, 18252, 19200, 20172, 21675, 22707, 23763, 24300, 24843, 27075, 28227, 30000, 30603

Offset

1,1

Links

Chai Wah Wu, Table of n, a(n) for n = 1..10000

Formula

Sequence is 3*(distinct elements in A198385).

Numbers of the form 3*m^2 where 2*m^2 is in A004431. - Chai Wah Wu, Oct 05 2017

Example

75 = 1^2 + 5^2 + 7^2 = 1 + 25 + 49, with 25 - 1 = 49 - 25 = 24.
675 = 3^2 + 15^2 + 21^2 = 9 + 225 + 441, with 225 - 9 = 441 - 225 = 216.

Prog

(PARI) t=4; k=3; while(t<=13000, i=k; e=0; v=t+i; while(i>1&&e==0, if(issquare(v), m=3*t; e=1; print1(m, ", ")); i+=-2; v+=i); k+=2; t+=k)

Crossrefs

Subsequence of A033428.

Cf. A000290, A000378, A004431, A134422, A292309, A292310, A292314, A292316.

Sequence in context: A258056 A174685 A158742 * A158765 A226741 A223078

Adjacent sequences: A292310 A292311 A292312 * A292314 A292315 A292316

Keyword

nonn

Author

Antonio Roldán, Sep 14 2017

Status

approved