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 A087085 #1 Sep 13 2003 03:00:00 %S A087085 0,0,2,48,3072,2621440,515396075520,6198106008766409342976, %T A087085 304893000761160863263183648258864317464576 %N A087085 Sum of the integer elements in the subsets of the subsets of the integers 1 to n. %D A087085 Alan Sutcliffe, Divisors and Common Factors in Sets of Integers, awaiting publication. %F A087085 n*(n-1)*2^(n-4+2^(n-1)) %e A087085 a(3)=48 since the 16 subsets of the sets ( ) (1) (2) (1,2) are ( ) (( )) ((1)) ((2)) ((1,2)) (( ) (1)) (( ) (2)) (( ) (1,2)) ((1) (2)) ((1) (1,2)) ((2) (1,2)) (( ) (1) (2)) (( ) (1) (1,2)) (( ) (2) (1,2)) ((1) (2) (1,2)) (( ) (1) (2) (1,2)) and the sum of the 32 integer elements is 48. %Y A087085 A001146 gives the number of subsets of the subsets of the integers 1 to n. A028369 gives the number of subset elements in the subsets of the subsets of the integers 1 to n. A087084 gives the number of integer elements in the subsets of the subsets of the integers 1 to n. %K A087085 easy,nonn %O A087085 0,3 %A A087085 Alan Sutcliffe (alansut(AT)ntlworld.com), Aug 13 2003