A156838 Row sums of triangle A156837

1, 3, 3, 7, 3, 13, 3, 17, 11, 17, 3, 51, 3, 21, 37, 55, 3, 83, 3, 113, 63, 29, 3, 271, 75, 33, 103, 223, 3, 453, 3, 329, 139, 41, 427, 897, 3, 45, 189, 1265, 3, 1267, 3, 651, 1277, 53, 3, 2943, 929, 1571, 313, 1001, 3, 3147, 2009, 4843, 387, 65, 3, 9159, 3, 69, 6541, 5459, 3647, 6753, 3, 2053, 559, 15299, 3, 25677, 3, 81

Offset

1,2

Comments

a(n) = 3 iff n is prime.

Links

Antti Karttunen, Table of n, a(n) for n = 1..10000

Formula

Row sums of triangle A156837.

Example

a(4) = 7 since row 4 of triangle A156837 = (3, 3, 0, 1).

Maple

A156838 := proc(n)
    add(A156837(n, k), k=1..n) ;
end proc: # R. J. Mathar, Mar 03 2013

Prog

(PARI)
A156348(n, k) = if(k<1 || k>n || n%k, 0, binomial(n/k-2+k, k-1)); \\ After R. J. Mathar's Maple-program in A156348
A156837(n, k) = sum(j=k, n, if(n%j, 0, A156348(j, k)));
A156838(n) = sumdiv(n, d, A156837(n, d)); \\ Antti Karttunen, Nov 30 2024

Crossrefs

A156837

Sequence in context: A062402 A347405 A294015 * A274845 A324048 A100587

Adjacent sequences: A156835 A156836 A156837 * A156839 A156840 A156841

Keyword

nonn,easy

Author

Gary W. Adamson & Mats Granvik, Feb 16 2009

Extensions

Extended beyond a(14) by R. J. Mathar, Mar 03 2013

More terms from Antti Karttunen, Nov 30 2024

Status

approved