A236858 Irregular table where row n contains numbers from 1 to the least common multiple (LCM) of {1, 2, ..., n}. Row 0 is given as a(0)=1.

1, 1, 1, 2, 1, 2, 3, 4, 5, 6, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60

Offset: 0

Author

Antti Karttunen, Feb 27 2014

Keywords

• nonn
• tabf
• easy

Comments

Numbers 1..A003418(n) followed by numbers 1..A003418(n+1), etc., where A003418(n) gives the least common multiple (LCM) of {1, 2, ..., n} for n >= 1 and A003418(0)=1.

Useful when computing irregular tables like A238280. Note that as A238280 begins with row 1, it starts referring to this sequence only from a(1) onward.

Examples

			The sequence can be viewed also as an irregular table that starts as:
0 | 1;
1 | 1;
2 | 1, 2;
3 | 1, 2, 3, 4, 5, 6;
4 | 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12;
...
		

Links

• Antti Karttunen, Rows 0..10 of the table, flattened

Crossrefs

A003418(n) gives the last term of each row n.

Cf. A220661, A236856, A236857, A238280.

Programs

Mathematica

Join[{1},Table[Range[LCM@@Range[n]],{n,6}]//Flatten] (* Harvey P. Dale, Apr 29 2019 *)

Scheme

(define (A236858 n) (- n (A236856 (- (A236857 n) 1))))

Formula

a(n) = n - A236856(A236857(n)- 1).