login
A225531
Number of ordered pairs (i, j) with i, j >= 0, i + j <= n and gcd(i, j) <= 1.
4
1, 3, 4, 6, 8, 12, 14, 20, 24, 30, 34, 44, 48, 60, 66, 74, 82, 98, 104, 122, 130, 142, 152, 174, 182, 202, 214, 232, 244, 272, 280, 310, 326, 346, 362, 386, 398, 434, 452, 476, 492, 532, 544, 586, 606, 630, 652, 698, 714, 756, 776
OFFSET
0,2
COMMENTS
This sequence is in reply to an extension request made in A100449.
Note that gcd(0,m) = m for any m.
LINKS
MATHEMATICA
f[n_] := Length[Complement[Union[Flatten[Table[If[i + j <= n && GCD[i, j] <= 1, {i, j}], {i, 0, n}, {j, 0, n}], 1]], {Null}]]; Table[f[n], {n, 0, 100}]
PROG
(PARI) alist(N) = my(c=2); vector(N, i, if(1==i, 1, c+=eulerphi(i-1))); \\ Ruud H.G. van Tol, Jul 09 2024
KEYWORD
nonn,easy
AUTHOR
Robert Price, May 09 2013
STATUS
approved