This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A244259 #22 Jul 16 2014 06:31:13 %S A244259 1,0,0,0,2,1,2,1,1,2,2,1,2,2,1,2,2,3,2,2,2,2,2,2,3,2,2,3,2,3,2,3,2,2, %T A244259 2,4,2,2,2,2,2,3,2,3,3,2,2,4,3,4,2,3,2,5,4,3,2,2,2,4,2,2,2,4,4,5,2,3, %U A244259 2,4,2,5,2,2,3,3,4,5,2,4,3,2,2,4,4,2,2,5,2,5,4,3,2,2,4,6 %N A244259 Number of non-twin isolated divisors of n. %C A244259 Number of divisors d of n such that neither the positive values d - 2 nor d - 1 nor d + 1 nor d + 2 divide n. %C A244259 An isolated divisor d is non-twin if neither the positive values d - 2 nor d + 2 divide n. %H A244259 Jens Kruse Andersen, <a href="/A244259/b244259.txt">Table of n, a(n) for n = 1..10000</a> %e A244259 The isolated divisors of 56 are: 4, 14, 28, 56. The non-twin divisors of 56 are: 1, 7, 8, 14, 28, 56. The non-twin isolated divisors of 56 are therefore 14, 28, 56. There are 3 of these, so a(56) = 3. %o A244259 (PARI) a(n) = sumdiv(n, d, (((d<=2) || (n % (d-2))) && ((d<=1) || (n % (d-1))) && (n % (d+1)) && (n % (d+2)))); \\ _Michel Marcus_, Jun 25 2014 %Y A244259 Cf. A132881 (number of isolated divisors of n), A243917 (number of non-twin divisors of n). %K A244259 nonn,easy %O A244259 1,5 %A A244259 _Juri-Stepan Gerasimov_, Jun 24 2014