Search: id:A074837
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%I A074837
%S A074837 6,18,42,54,66,78,102,114,126,138,162,174,186,198,222,234,246,258,282,
%T A074837 294,306,318,342,354,366,378,402,414,426,438,462,474,486,498,522,534,
%U A074837 546,558,582,594,606,618,642,654,666,678,702,714,726,738,762,774,786
%N A074837 Numbers n such that the penultimate 3 divisors of n sum to n.
%C A074837 It seems that only numbers that are 6 mod 12 are present except for multiples 
               of 30.
%e A074837 18 has the divisors 1,2,3,6,9,18. The penultimate 3 are 3,6,9, which 
               sum to 18.
%t A074837 Select[Range[1000],Length[Divisors[ # ]]>3 && Sum[Divisors[ # ][[ -i]],
               {i,2,4}]==# &] - Stefan Steinerberger (stefan.steinerberger(AT)gmail.com), 
               Aug 01 2007
%o A074837 (PARI) for (n=1,300,dn=divisors(n); dnl=length(dn); if (dnl>3,if (n==dn[dnl-1]+dn[dnl-2]+dn[dnl-3],
               print(n))))
%Y A074837 Sequence in context: A015224 A163983 A023620 this_sequence A015942 A009945 
               A011930
%Y A074837 Adjacent sequences: A074834 A074835 A074836 this_sequence A074838 A074839 
               A074840
%K A074837 nonn
%O A074837 1,1
%A A074837 Jon Perry (perry(AT)globalnet.co.uk), Sep 09 2002
%E A074837 More terms from Stefan Steinerberger (stefan.steinerberger(AT)gmail.com), 
               Aug 01 2007

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