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A143537 Triangle read by rows: T(n,k) = number of primes in the interval [k..n], n >= 1, 1 <= k <= n. 1
0, 1, 1, 2, 2, 1, 2, 2, 1, 0, 3, 3, 2, 1, 1, 3, 3, 2, 1, 1, 0, 4, 4, 3, 2, 2, 1, 1, 4, 4, 3, 2, 2, 1, 1, 0, 4, 4, 3, 2, 2, 1, 1, 0, 0, 4, 4, 3, 2, 2, 1, 1, 0, 0, 0, 5, 5, 4, 3, 3, 2, 2, 1, 1, 1, 1, 5, 5, 4, 3, 3, 2, 2, 1, 1, 1, 1, 0, 6, 6, 5, 4, 4, 3, 3, 2, 2, 2, 2, 1, 1 (list; table; graph; refs; listen; history; text; internal format)
OFFSET

1,4

COMMENTS

Old name: triangle read by rows, A000012 * A143536, 1<=k<=n.

LINKS

Table of n, a(n) for n=1..91.

FORMULA

T(n,k) = pi(n) - pi(k-1), where pi = A000720. - Ilya Gutkovskiy, Mar 19 2020

EXAMPLE

Triangle T(n,k) begins:

n\k 1  2  3  4  5  6  7  8 ...

1:  0;

2:  1, 1;

3:  2, 2, 1;

4:  2, 2, 1, 0;

5:  3, 3, 2, 1, 1;

6:  3, 3, 2, 1, 1, 0;

7:  4, 4, 3, 2, 2, 1, 1;

8:  4, 4, 3, 2, 2, 1, 1, 0;

...

CROSSREFS

Row sums are A034387.

Column k=1 gives A000720.

Main diagonal gives A010051.

T(2n,n) gives A035250.

Cf. A143536.

Sequence in context: A285930 A300480 A342870 * A125916 A283468 A100244

Adjacent sequences:  A143534 A143535 A143536 * A143538 A143539 A143540

KEYWORD

nonn,tabl

AUTHOR

Gary W. Adamson, Aug 23 2008

EXTENSIONS

New name and corrected by Ilya Gutkovskiy, Mar 19 2020

STATUS

approved

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Last modified May 15 06:46 EDT 2021. Contains 343909 sequences. (Running on oeis4.)