OFFSET
1,2
COMMENTS
Row sums = A143127. - Gary W. Adamson, Jul 26 2008
LINKS
G. C. Greubel, Table of n, a(n) for the first 50 rows, flattened
FORMULA
EXAMPLE
T(4,2)=7 because 2 has 2 divisors, 3 has 2 divisors and 4 has 3 divisors.
Triangle begins:
1;
3, 2;
5, 4, 2;
8, 7, 5, 3;
10, 9, 7, 5, 2;
...
MAPLE
with(numtheory): T:=(n, k)->add(tau(j), j=k..n): for n from 1 to 13 do seq(T(n, k), k=1..n) od; # yields sequence in triangular form
MATHEMATICA
T[n_, n_] := DivisorSigma[0, n]; T[n_, k_] := Sum[DivisorSigma[0, j], {j, k, n}]; Table[T[n, k], {n, 1, 10}, {k, 1, n}] // Flatten (* G. C. Greubel, Sep 03 2017 *)
CROSSREFS
KEYWORD
nonn,tabl
AUTHOR
Emeric Deutsch, Aug 02 2005
STATUS
approved