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.

A339496 T(n, k) = Sum(divisors(k) union {k*j : j = 2..floor(n/k)}). Triangle read by rows.

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%I A339496 #9 Dec 31 2020 13:13:19
%S A339496 1,3,3,6,3,4,10,7,4,7,15,7,4,7,6,21,13,10,7,6,12,28,13,10,7,6,12,8,36,
%T A339496 21,10,15,6,12,8,15,45,21,19,15,6,12,8,15,13,55,31,19,15,16,12,8,15,
%U A339496 13,18,66,31,19,15,16,12,8,15,13,18,12,78,43,31,27,16,24,8,15,13,18,12,28
%N A339496 T(n, k) = Sum(divisors(k) union {k*j : j = 2..floor(n/k)}). Triangle read by rows.
%C A339496 For the connection with paths in the divisor graph of {1,...,n} see the comment in A339492.
%e A339496 The triangle starts:
%e A339496 [1]                       1;
%e A339496 [2]                      3, 3;
%e A339496 [3]                    6, 3, 4;
%e A339496 [4]                  10, 7, 4, 7;
%e A339496 [5]                15, 7, 4, 7, 6;
%e A339496 [6]              21, 13, 10, 7, 6, 12;
%e A339496 [7]            28, 13, 10, 7, 6, 12, 8;
%e A339496 [8]          36, 21, 10, 15, 6, 12, 8, 15;
%e A339496 [9]        45, 21, 19, 15, 6, 12, 8, 15, 13;
%e A339496 [10]     55, 31, 19, 15, 16, 12, 8, 15, 13, 18.
%p A339496 t := (n, k) -> NumberTheory:-Divisors(k) union {seq(k*j,j=2..n/k)}:
%p A339496 T := (n, k) -> add(j, j = t(n, k)):
%p A339496 for n from 1 to 10 do seq(T(n, k), k=1..n) od;
%Y A339496 T(n, 1) = A000217(n), T(n, n) = A000203(n), T(2n, n) = A224880(n).
%Y A339496 Cf. A339491, A339492, A339489.
%K A339496 nonn,tabl
%O A339496 1,2
%A A339496 _Peter Luschny_, Dec 31 2020