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.
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
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