A173330 - OEIS

A173330

First of two intermediate sequences for integral solution of A002144(n)=x^2+y^2.

1, 10, 1, 5, 1, 5, 46, 5, 70, 5, 9, 1, 106, 106, 126, 142, 146, 13, 9, 186, 1, 214, 13, 226, 1, 13, 9, 5, 17, 13, 306, 9, 5, 17, 366, 17, 378, 1, 406, 406, 17, 442, 21, 442, 5, 510, 21, 538, 13, 1, 570, 5, 17, 598, 25, 13, 25, 650, 1, 5, 694, 706, 9, 742, 25, 17, 786, 5, 25

(list; graph; refs; listen; history; text; internal format)

OFFSET

1,2

COMMENTS

A002972(n) = MIN(a(n), A002144(n) - a(n)).

REFERENCES

H. Davenport, The Higher Arithmetic (Cambridge University Press 7th ed., 1999), ch. V.3, p.122.

LINKS

Table of n, a(n) for n=1..69.

FORMULA

a(n) = (2k)! / 2(k!)^2 mod p, where p = 4*k+1 = A002144(n).

EXAMPLE