A225531 Number of ordered pairs (i, j) with i, j >= 0, i + j <= n and gcd(i, j) <= 1.

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

Robert Price, Table of n, a(n) for n = 0..400

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}]

Crossrefs

Cf. A018805, A027430, A100448, A100449, A100450, A213207, A213208, A213212, A213213.

Sequence in context: A232721 A227956 A320592 * A129295 A192276 A049305

Adjacent sequences: A225528 A225529 A225530 * A225532 A225533 A225534

Keyword

nonn,easy

Author

Robert Price, May 09 2013

Status

approved