A266742 Irregular triangle read by rows: T(n,k) = floor(n/(prime(k)-1)), n>=1, 1 <= k <= pi(n+1), where pi is A000720.

1, 2, 1, 3, 1, 4, 2, 1, 5, 2, 1, 6, 3, 1, 1, 7, 3, 1, 1, 8, 4, 2, 1, 9, 4, 2, 1, 10, 5, 2, 1, 1, 11, 5, 2, 1, 1, 12, 6, 3, 2, 1, 1, 13, 6, 3, 2, 1, 1, 14, 7, 3, 2, 1, 1, 15, 7, 3, 2, 1, 1, 16, 8, 4, 2, 1, 1, 1, 17, 8, 4, 2, 1, 1, 1, 18, 9, 4, 3, 1, 1, 1, 1

Offset: 1

Author

N. J. A. Sloane, Jan 08 2016

Keywords

• nonn
• tabf

Examples

			Triangle begins:
[1]
[2, 1]
[3, 1]
[4, 2, 1]
[5, 2, 1]
[6, 3, 1, 1]
[7, 3, 1, 1]
[8, 4, 2, 1]
[9, 4, 2, 1]
[10, 5, 2, 1, 1]
[11, 5, 2, 1, 1]
[12, 6, 3, 2, 1, 1]
[13, 6, 3, 2, 1, 1]
[14, 7, 3, 2, 1, 1]
...
		

Links

• H. T. Davis, Tables of the Mathematical Functions, Vols. 1 and 2, 2nd ed., 1963, Vol. 3 (with V. J. Fisher), 1962; Principia Press of Trinity Univ., San Antonio, TX. [Annotated scan of pages 204-208 of Volume 2.] See Table 1 on page 205.

Crossrefs

Cf. A000720, A002443, A002444, A266743.

Programs

Maple

with(numtheory);
f:=n->[seq(floor(n/(ithprime(i)-1)),i=1..pi(n+1))];
for n from 1 to 20 do lprint(f(n)); od: