A147594 a(n) = sigma_0(n + a(n-1)), with a(1) = 1.

1, 2, 2, 4, 3, 3, 4, 6, 4, 4, 4, 5, 6, 6, 4, 6, 2, 6, 3, 2, 2, 8, 2, 4, 2, 6, 4, 6, 4, 4, 4, 9, 8, 8, 2, 4, 2, 8, 2, 8, 3, 6, 3, 2, 2, 10, 4, 6, 4, 8, 2, 8, 2, 8, 6, 4, 2, 12, 2, 4, 4, 8, 2, 8, 2, 6, 2, 8, 4, 4, 6, 8, 5, 2, 4, 10, 4, 4, 2, 4, 4, 4, 4, 8, 4

Offset

1,2

Links

G. C. Greubel, Table of n, a(n) for n = 1..10000

Formula

a(n) = A000005(n + a(n-1)), with a(1) = 1.

Mathematica

RecurrenceTable[{a[1]==1, a[n]==DivisorSigma[0, n+a[n-1]]}, a, {n, 20}] (* Harvey P. Dale, Apr 25 2016 *)

Prog

(Magma)
[n le 1 select 1 else NumberOfDivisors(n + Self(n-1)): n in [1..100]]; // G. C. Greubel, Aug 06 2024
(SageMath)
def A147594(n): return 1 if n==1 else sigma(n + A147594(n-1), 0)
[A147594(n) for n in range(1, 101)] # G. C. Greubel, Aug 06 2024

Crossrefs

Cf. A000005.

Sequence in context: A154417 A292421 A205563 * A305425 A212652 A303691

Adjacent sequences: A147591 A147592 A147593 * A147595 A147596 A147597

Keyword

easy,nonn

Author

Ctibor O. Zizka, Nov 08 2008

Extensions

More terms from Harvey P. Dale, Apr 25 2016

Status

approved