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A109386 G.f. is the logarithm of the g.f. of A107742: Sum_{n>=1} (a(n)/n)*x^n = Log( Sum_{n>=0} A107742(n)*x^n ). 8
1, 3, 7, 7, 11, 21, 15, 15, 34, 33, 23, 49, 27, 45, 77, 31, 35, 102, 39, 77, 105, 69, 47, 105, 86, 81, 142, 105, 59, 231, 63, 63, 161, 105, 165, 238, 75, 117, 189, 165, 83, 315, 87, 161, 374, 141, 95, 217, 162, 258, 245, 189, 107, 426, 253, 225, 273, 177, 119, 539, 123, 189, 510, 127, 297 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

Seiichi Manyama, Table of n, a(n) for n = 1..10000

FORMULA

a(n) = Sum_{d|n} d * Sum_{m|d} (m mod 2).

G.f.: Sum_{n>=1} a(n)/n*x^n = Sum_{j>=1} Sum_{i>=1} log(1+x^(i*j)).

G.f.: Sum_{n>0} n*A000005(n)*x^n/(1+x^n). a(n) = A060640(n) if n is odd, else a(n) = A060640(n)-2*A060640(n/2). Multiplicative with a(2^e) = 2^(e+1)-1 and a(p^e) = (p^(e+2)*(e+1)-p^(e+1)*(e+2)+1)/(p-1)^2 for p>2. - Vladeta Jovovic, Jul 05 2005

Also g.f.: Sum_{n>0} n*A001227(n)*x^n/(1-x^n). a(n) = Sum_{d|n} d*A001227(d). - Vladeta Jovovic, Jul 05 2005

Also a(n) = Sum_{d|n} d*A000593(n/d). - Vladeta Jovovic, Jul 05 2005

A107742(n) = (1/n)*Sum_{k=1..n} a(k)*A107742(n-k). - Vladeta Jovovic, Jul 05 2005

MATHEMATICA

a[n_] := DivisorSum[n, #*DivisorSum[#, Mod[#, 2]&]&]; Array[a, 65] (* Jean-Fran├žois Alcover, Dec 23 2015 *)

PROG

(PARI) a(n)=sumdiv(n, d, d*sumdiv(d, m, m%2))

(PARI)N=66; x='x+O('x^N); /* that many terms */

c=sum(j=1, N, j*x^j);

t=log( 1/prod(j=0, N, eta(x^(2*j+1))) );

gf=serconvol(t, c);

Vec(gf) /* show terms */

/* Joerg Arndt, May 03, 2008 */

CROSSREFS

Cf. A107742.

Sum_{d|n} d^k*A000593(n/d): A288417 (k=0), this sequence (k=1), A288418 (k=2), A288419 (k=3), A288420 (k=4).

Sequence in context: A179873 A080457 A119644 * A024612 A227025 A073881

Adjacent sequences:  A109383 A109384 A109385 * A109387 A109388 A109389

KEYWORD

nonn,mult

AUTHOR

Paul D. Hanna, Jun 26 2005

STATUS

approved

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Last modified June 17 22:14 EDT 2021. Contains 345086 sequences. (Running on oeis4.)