login
The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A339496 T(n, k) = Sum(divisors(k) union {k*j : j = 2..floor(n/k)}). Triangle read by rows. 3

%I

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

%C For the connection with paths in the divisor graph of {1,...,n} see the comment in A339492.

%e The triangle starts:

%e [1] 1;

%e [2] 3, 3;

%e [3] 6, 3, 4;

%e [4] 10, 7, 4, 7;

%e [5] 15, 7, 4, 7, 6;

%e [6] 21, 13, 10, 7, 6, 12;

%e [7] 28, 13, 10, 7, 6, 12, 8;

%e [8] 36, 21, 10, 15, 6, 12, 8, 15;

%e [9] 45, 21, 19, 15, 6, 12, 8, 15, 13;

%e [10] 55, 31, 19, 15, 16, 12, 8, 15, 13, 18.

%p t := (n, k) -> NumberTheory:-Divisors(k) union {seq(k*j,j=2..n/k)}:

%p T := (n, k) -> add(j, j = t(n, k)):

%p for n from 1 to 10 do seq(T(n, k), k=1..n) od;

%Y T(n, 1) = A000217(n), T(n, n) = A000203(n), T(2n, n) = A224880(n).

%Y Cf. A339491, A339492, A339489.

%K nonn,tabl

%O 1,2

%A _Peter Luschny_, Dec 31 2020

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified May 9 10:09 EDT 2021. Contains 343728 sequences. (Running on oeis4.)