A283677 a(n) = lcm(b(b(n)), b(n-b(n)+1)) where b(n) = A004001(n).

1, 1, 1, 2, 2, 2, 2, 6, 3, 12, 12, 4, 4, 4, 4, 20, 5, 30, 35, 35, 42, 24, 24, 56, 56, 56, 8, 8, 8, 8, 8, 72, 9, 90, 99, 36, 36, 60, 130, 70, 70, 154, 165, 165, 60, 60, 60, 195, 208, 208, 112, 112, 112, 240, 240, 240, 240, 16, 16, 16, 16, 16, 16, 272, 17, 306, 323, 340, 357, 357, 126, 198, 414, 72, 72, 456, 475, 494

Offset: 1

Author

Altug Alkan, Mar 14 2017

Keywords

• nonn
• look

Comments

See the order of certain subsequences in scatterplot link.

Examples

			a(4) = lcm(A004001(A004001(4)), A004001(4-A004001(4)+1)) = lcm(1, 2) = 2.
		

Links

• Altug Alkan, Table of n, a(n) for n = 1..10000
• Altug Alkan, Alternative Scatterplot of A283677
• Index entries for sequences related to lcm's

Crossrefs

Cf. A004001, A080677.

Cf. also A283470, A283673.

Programs

Mathematica

b[1] = b[2] = 1; b[n_] := b[n] = b[b[n - 1]] + b[n - b[n - 1]]; Table[LCM[b[b[n]], b[n + 1 - b[n]]], {n, 1, 78}] (* Indranil Ghosh, Mar 14 2017 *)

PARI

a=vector(1000); a[1]=a[2]=1; for(n=3, #a, a[n]=a[a[n-1]]+a[n-a[n-1]]); va = vector(1000, n, lcm(a[a[n]], a[n+1-a[n]]))

Scheme

(define (A283677 n) (lcm (A004001 (A004001 n)) (A004001 (+ 1 (- n (A004001 n)))))) ;; (Code for A004001 given under that entry). - Antti Karttunen, Mar 18 2017

Formula

a(n) = lcm(A004001(A004001(n)), A004001(A080677(n))). - Antti Karttunen, Mar 18 2017