OFFSET
1,2
COMMENTS
Essentially a duplicate of A053222.
Convolved with the nonzero terms of A000217 gives A175254, the volume of the stepped pyramid described in A245092.
Convolved with the nonzero terms of A046092 gives A244050, the volume of the stepped pyramid described in A244050.
For the correspondence between divisors and partitions see A336811.
FORMULA
a(n) = A053222(n-1) for n>1. - Michel Marcus, Jan 22 2021
MAPLE
a:= n-> (s-> s(n)-s(n-1))(numtheory[sigma]):
seq(a(n), n=1..77); # Alois P. Heinz, Jan 21 2021
MATHEMATICA
Join[{1}, Differences @ Table[DivisorSigma[1, n], {n, 1, 100}]] (* Amiram Eldar, Jan 21 2021 *)
PROG
(PARI) a(n) = if (n==1, 1, sigma(n)-sigma(n-1)); \\ Michel Marcus, Jan 22 2021
CROSSREFS
1 together with A053222.
Cf. A000203 (partial sums).
KEYWORD
sign,easy
AUTHOR
Omar E. Pol, Jan 21 2021
STATUS
approved