cp's OEIS Frontend

A104076 If k(m) is the m-th divisor (when the divisors are ordered by size) of n, then a(n) = gcd(k(1)+k(2), k(2)+k(3), k(3)+k(4), ..., k(j-1)+k(j)), where j is the number of divisors of n.

%I A104076 #18 Oct 26 2019 16:26:24
%S A104076 3,4,3,6,1,8,3,4,1,12,1,14,3,4,3,18,1,20,3,2,1,24,1,6,3,4,1,30,1,32,3,
%T A104076 2,1,6,1,38,3,4,1,42,1,44,3,2,1,48,1,8,1,4,1,54,1,2,1,2,1,60,1,62,3,2,
%U A104076 3,6,1,68,3,2,1,72,1,74,3,4,1,2,1,80,1,4,1,84,1,2,3,4,1,90,1,4,3,2,1,6,1,98
%N A104076 If k(m) is the m-th divisor (when the divisors are ordered by size) of n, then a(n) = gcd(k(1)+k(2), k(2)+k(3), k(3)+k(4), ..., k(j-1)+k(j)), where j is the number of divisors of n.
%H A104076 Harvey P. Dale, <a href="/A104076/b104076.txt">Table of n, a(n) for n = 2..1000</a>
%e A104076 The divisors of 14 are 1,2,7,14. So a(14) = gcd(1+2, 2+7, 7+14) = 3.
%p A104076 A104076 := proc(n) local dvs ; dvs := sort(convert(numtheory[divisors](n),list)) ; igcd(seq( op(i,dvs)+op(i+1,dvs), i=1..nops(dvs)-1)) ; end: for n from 2 to 140 do printf("%d,",A104076(n)) ; od: # _R. J. Mathar_, Sep 05 2008
%t A104076 Table[GCD@@(Total/@Partition[Divisors[n],2,1]),{n,2,100}] (* _Harvey P. Dale_, Dec 18 2018 *)
%Y A104076 Cf. A143771.
%K A104076 nonn
%O A104076 2,1
%A A104076 _Leroy Quet_, Aug 31 2008
%E A104076 Extended by _R. J. Mathar_, Sep 05 2008
%E A104076 Definition corrected by _Leroy Quet_, Sep 21 2008