cp's OEIS Frontend

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.

A348161 Number of factorizations of (n,n) into one or two pairs (i,j) with i > 0, j > 0 (and if i=1 then j=1).

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%I A348161 #5 Oct 03 2021 19:28:14
%S A348161 1,1,1,3,1,5,1,5,3,5,1,13,1,5,5,9,1,13,1,13,5,5,1,25,3,5,5,13,1,25,1,
%T A348161 13,5,5,5,33,1,5,5,25,1,25,1,13,13,5,1,41,3,13,5,13,1,25,5,25,5,5,1,
%U A348161 61,1,5,13,19,5,25,1,13,5,25,1,61,1,5,13,13,5,25
%N A348161 Number of factorizations of (n,n) into one or two pairs (i,j) with i > 0, j > 0 (and if i=1 then j=1).
%F A348161 For n > 1, a(n) = ceiling((tau(n)-2)*tau(n)/2) + 1, where tau(n) = A000005(n).
%e A348161 (4,4) = (2,4)*(2,1) = (2,2)*(2,2), so a(4)=3.
%Y A348161 Main diagonal of A348157.
%Y A348161 Cf. A051707 (any number of pairs).
%K A348161 nonn
%O A348161 1,4
%A A348161 _Sean A. Irvine_, Oct 03 2021