A236856 Partial sums of A003418 starting summing from A003418(1), with a(0) = 0.

0, 1, 3, 9, 21, 81, 141, 561, 1401, 3921, 6441, 34161, 61881, 422241, 782601, 1142961, 1863681, 14115921, 26368161, 259160721, 491953281, 724745841, 957538401, 6311767281, 11665996161, 38437140561, 65208284961, 145521718161, 225835151361, 2554924714161

Offset

0,3

Comments

Similar comments about the trailing digits apply here as in A173185.

a(n) gives the position of the last element of row n in irregular tables like A238280.

From a(2)=3 onward all terms are divisible by three.

a(n) is divisible by 73 for n >= 72. Therefore a(n)/3 is prime for only 13 values of n: 3, 4, 6, 8, 9, 12, 16, 22, 23, 31, 35, 48 and 53. - Amiram Eldar, Sep 19 2022

Links

Antti Karttunen, Table of n, a(n) for n = 0..250

Formula

a(n) = A173185(n)-1.

Mathematica

Prepend[Accumulate @ Table[LCM @@ Range[n], {n, 1, 30}], 0] (* Amiram Eldar, Sep 19 2022 *)

Prog

(Scheme) (define (A236856 n) (if (< n 2) n (+ (A236856 (- n 1)) (A003418 n))))

Crossrefs

One less than A173185.

Cf. A003418, A007489, A231722, A236857, A236858.

Sequence in context: A073947 A062811 A363693 * A338534 A318843 A001470

Adjacent sequences: A236853 A236854 A236855 * A236857 A236858 A236859

Keyword

nonn

Author

Antti Karttunen, Feb 27 2014

Status

approved