A355149 Partial sums of A351743.

1, 2, 4, 5, 10, 12, 15, 20, 24, 27, 28, 56, 57, 114, 116, 145, 150, 156, 169, 170, 340, 341, 682, 684, 855, 860, 1032, 1035, 1150, 1152, 1161, 1204, 1232, 1243, 1356, 1368, 1387, 1460, 1480, 1517, 1558, 1596, 1617, 1628, 1776, 1779, 2372, 2376, 2673, 2674

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).

Example

a(3) = A351743(1) + A351743(2) + A351743(3) = 1 + 1 + 2 = 4.

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

Cf. A351743.

Sequence in context: A177186 A375029 A260385 * A022944 A370593 A241822

Adjacent sequences: A355146 A355147 A355148 * A355150 A355151 A355152

Keyword

nonn

Author

Michael De Vlieger, Rémy Sigrist and David James Sycamore, Jun 21 2022

Status

approved