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 A073110 Number of permutations p of (1,2,3,...,n) such that sigma(1+p(1))+sigma(2+p(2))+...+sigma(n+p(n))=2*n^2. 0
 0, 1, 0, 2, 10, 37, 121, 725, 5160, 31794, 279136, 2137531, 21305316, 213311303, 2457648287, 30357607661, 387013387043, 5245097770693 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,4 COMMENTS It seems that for any permutation p of (1,2,3,...,n) for n>3, the equation: sigma(1+p(1))+sigma(2+p(2))+...+sigma(n+p(n))=m*n^2 has solutions for m=2 only. LINKS PROG (PARI) a(n)=sum(k=1, n!, if(sum(i=1, n, sigma(i+component(numtoperm(n, k), i)))-2*n^2, 0, 1)) CROSSREFS Sequence in context: A236767 A154323 A191349 * A034547 A246604 A124646 Adjacent sequences:  A073107 A073108 A073109 * A073111 A073112 A073113 KEYWORD nonn AUTHOR Benoit Cloitre, Aug 19 2002 EXTENSIONS 2 more terms from Ryan Propper, Aug 27 2005 a(12)-a(18) from Robert Gerbicz, Nov 21 2010 STATUS approved

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Last modified September 21 20:10 EDT 2021. Contains 347598 sequences. (Running on oeis4.)