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 A179503 a(n) = Sum_{k=0..n} C(n,k)*sigma(n,k)*sigma(n,n-k) for n>0 with a(0)=1. 0
 1, 2, 38, 352, 8372, 115584, 4900168, 109607936, 5462020742, 210689453568, 11579697409448, 585804318154752, 39828186864515408, 2482740302750253056, 188760627291893696552, 14430243196023615258624 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,2 COMMENTS sigma(n,k) denotes the sum of the k-th power of the divisors of n. LINKS Table of n, a(n) for n=0..15. EXAMPLE a(2) = 1*2*5 + 2*3*3 + 1*5*2. a(3) = 1*2*28 + 3*4*10 + 3*10*4 + 1*28*2. a(4) = 1*3*273 + 4*7*73 + 6*21*21 + 4*73*7 + 1*273*3. a(5) = 1*2*3126 + 5*6*626 + 10*26*126 + 10*126*26 + 5*626*6 + 1*3126*2. a(6) = 1*4*47450 + 6*12*8052 + 15*50*1394 + 20*252*252 + 15*1394*50 + 6*8052*12 + 1*47450*4. PROG (PARI) a(n)=if(n==0, 1, sum(k=0, n, binomial(n, k)*sigma(n, k)*sigma(n, n-k))) CROSSREFS Sequence in context: A226402 A217214 A303618 * A126731 A216357 A046845 Adjacent sequences: A179500 A179501 A179502 * A179504 A179505 A179506 KEYWORD nonn AUTHOR Paul D. Hanna, Sep 21 2010 STATUS approved

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Last modified June 21 19:43 EDT 2024. Contains 373558 sequences. (Running on oeis4.)