来自在线整数百科全书的问候语!http://oeis.org/ Search: id:a089912 Showing 1-1 of 1 %I A089912 %S A089912 1,3,4,5,6,11,8,9,10,16,12,18,14,21,23,17,18,26,20,28,30,31,24,33,26, %T A089912 36,28,37,30,57,32,33,45,46,47,45,38,51,52,51,42,77,44,55,58,61,48,62, %U A089912 50,66,67,64,54,71,70,68,74,76,60,100,62,81,77,65,82,113,68,82,89,118,72 %N A089912 a(n) gives sum of number of common unitary divisors of n and m, where m runs from 1 to n. %H A089912 Amiram Eldar,n,a(n)n=1…10000的表%t A089912 udiv[n_] := Select[Divisors[n], GCD[#, n/#]==1 &]; a[n_] := Module[{d = udiv[n]}, Sum[Length[Intersection[d, udiv[k]]], {k,1,n}]]; Array[a, 100] (* _Amiram Eldar_, Aug 10 2019 *) %o A089912 (PARI) a(n) = {sdivn = Set(); fordiv(n, d, if (gcd(d, n/d) == 1, sdivn = setunion(sdivn, Set(d)))); s = 0; for (m=1, n, sdivm = Set(); fordiv(m, d, if (gcd(d, m/d) == 1, sdivm = setunion(sdivm, Set(d)))); s += length(setintersect(sdivn, sdivm));); return (s);} \\ _Michel Marcus_, Jul 15 2013 %Y A089912 Cf. A034444, A034448. %K A089912 easy,nonn %O A089912 1,2 %A A089912 _Naohiro Nomoto_, Jan 11 2004 # Content is available under The OEIS End-User License Agreement: http://oeis.org/LICENSE