OFFSET
1,2
COMMENTS
Number of lattice points (x,y) in the region 1 <= x <= n, 1 <= y <= n - A010051(n); see example.
This sequence gives the row sums of the triangle A257232. - Wolfdieter Lang, Apr 21 2015
LINKS
Reinhard Zumkeller, Table of n, a(n) for n = 1..10000
Eric Weisstein's World of Mathematics, Prime Counting Function
Wikipedia, Prime-counting function
FORMULA
EXAMPLE
10 . x
9 . x x
8 . x x x
7 . . x x x
6 . x x x x x
5 . . x x x x x
4 . x x x x x x x
3 . . x x x x x x x
2 . . x x x x x x x x
1 . x x x x x x x x x x
0 .__.__.__.__.__.__.__.__.__.__.
0 1 2 3 4 5 6 7 8 9 10
MATHEMATICA
Table[n (n + 1)/2 - PrimePi[n], {n, 1, 50}]
PROG
(Magma) [n*(n + 1)/2 - #PrimesUpTo(n): n in [1..60] ]; // Vincenzo Librandi, Apr 12 2015
(PARI) vector(80, n, n*(n+1)/2 - primepi(n)) \\ Michel Marcus, Apr 13 2015
(Haskell)
a256885 n = a000217 n - a000720 n -- Reinhard Zumkeller, Apr 21 2015
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Wesley Ivan Hurt, Apr 11 2015
EXTENSIONS
Edited, following the hint by Reinhard Zumkeller to change the offset. - Wolfdieter Lang, Apr 22 2015
STATUS
approved