A302690 - OEIS

A302690

a(n) is the smallest integer m such that m*n is a sum of two squares but not one.

2, 1, 6, 2, 1, 3, 14, 1, 2, 1, 22, 6, 1, 7, 3, 2, 1, 1, 38, 1, 42, 11, 46, 3, 2, 1, 6, 14, 1, 3, 62, 1, 66, 1, 7, 2, 1, 19, 3, 1, 1, 21, 86, 22, 1, 23, 94, 6, 2, 1, 3, 1, 1, 3, 11, 7, 114, 1, 118, 3, 1, 31, 14, 2, 1, 33, 134, 1, 138, 7, 142, 1, 1, 1, 6, 38, 154, 3, 158

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OFFSET

1,1

COMMENTS

Previous name was: a(n) is the smallest integer m such that A002828(m*n) = 2.

All terms are squarefree.

Using the sum of two squares theorem it is easy to see that a(n) is either A363340(n) (if A363340(n)*n is not a square) or 2*A363340(n) (if A363340(n)*n is a square). - Peter Schorn, Jul 20 2023

LINKS

Table of n, a(n) for n=1..79.

FORMULA

a(n^2) = 2.

MAPLE

A302690 := proc(n)

local k ;

for k from 1 do

if A002828(k*n) = 2 then

return k;

end if;

end do: