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%I #14 Sep 14 2024 01:41:01
%S 3,4,7,8,9,10,12,13,16,17,19,20,21,22,24,25,26,27,28,29,30,31,33,34,
%T 35,36,37,38,39,40,41,42,44,45,46,47,48,49,50,51,52,53,54,55,56,58,59,
%U 60,61,62,63,64,65,66,67,68,69,70,71,73,75,76,77,78,81,82,83,84,85,86,87,89
%N Numbers n such that sigma(n) can be represented as Sum_{i=0..k} sigma(m+i), with k>0.
%C Is it true that every integer n ultimately has sigma(n) representable like this?
%e sigma(61) = 62 = sigma(13) + sigma(14) + sigma(15) = 14 + 24 + 24.
%o (PARI) isok(n)=my(m=sigma(n)); for(k=1, m\2, my(s=sigma(k),j=k); while(s<m, j++; s+=sigma(j); if(s==m, return(1)))); 0 \\ _Andrew Howroyd_, Sep 13 2024
%Y Cf. A086987 gives values of sigma, A000203.
%K nonn
%O 1,1
%A _Jon Perry_, Jul 27 2003
%E Missing a(52)=64 inserted by _Andrew Howroyd_, Sep 13 2024