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A339496 T(n, k) = Sum(divisors(k) union {k*j : j = 2..floor(n/k)}). Triangle read by rows. 3
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, 21, 10, 15, 6, 12, 8, 15, 45, 21, 19, 15, 6, 12, 8, 15, 13, 55, 31, 19, 15, 16, 12, 8, 15, 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 (list; table; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

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

LINKS

Table of n, a(n) for n=1..78.

EXAMPLE

The triangle starts:

[1]                       1;

[2]                      3, 3;

[3]                    6, 3, 4;

[4]                  10, 7, 4, 7;

[5]                15, 7, 4, 7, 6;

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

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

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

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

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

MAPLE

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

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

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

CROSSREFS

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

Cf. A339491, A339492, A339489.

Sequence in context: A034188 A184849 A335870 * A336422 A040007 A110634

Adjacent sequences:  A339493 A339494 A339495 * A339497 A339498 A339499

KEYWORD

nonn,tabl

AUTHOR

Peter Luschny, Dec 31 2020

STATUS

approved

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Last modified May 17 05:13 EDT 2021. Contains 343965 sequences. (Running on oeis4.)