OFFSET
1,2
COMMENTS
a(n) is odd iff n mod 3 = 1. Parity of a(n) is related to that of A351743(n).
LINKS
Michael De Vlieger, Table of n, a(n) for n = 1..10000
FORMULA
Conjecture: a(n + 42) = 3645*a(n) + b(n) for n >= 138 (where b is 42-periodic).
MATHEMATICA
nn = 50, a[1] = m = s = 1; Do[If[m == 1, Set[k, s], Set[k, s]; While[GCD[m, k] > 1, k /= GCD[m, k]]]; m = k; s += k; a[n] = s, {n, 2, nn}]; Array[a, nn]
PROG
(PARI) { s=0; for (n=1, 50, if (n==1, v=1, w=s; while (1 < g=gcd(w, v), w /= g); v=w); print1 (s+=v", ")) }
CROSSREFS
KEYWORD
nonn
AUTHOR
STATUS
approved