A063750 Number of divisors (A000005) of the Wonderful Demlo numbers A002477.

1, 3, 9, 9, 9, 243, 9, 81, 45, 81, 9, 2187, 27, 81, 729, 729, 9, 10935, 3, 2187, 2187, 1215, 3, 59049, 243, 729, 567, 6561, 243, 1594323, 27, 177147, 729, 729, 2187, 295245, 27, 27, 729, 177147, 81, 7971615, 81, 98415, 32805, 729

Offset: 1

Author

Jason Earls, Aug 11 2001

Keywords

• nonn

Links

• Amiram Eldar, Table of n, a(n) for n = 1..352 (terms 1..80 from Harry J. Smith)

Crossrefs

Cf. A000005, A000042, A002477, A048691.

Programs

GAP

a:=n->((10^n-1)/9)^2;;  A063750:=List([1..50],n->Tau(a(n))); # Muniru A Asiru, Feb 17 2018

Maple

a:=n->((10^n-1)/9)^2: A063750:=[seq(numtheory[tau](a(n)),n=1..50)]; # Muniru A Asiru, Feb 17 2018

Mathematica

Array[DivisorSigma[0, FromDigits[PadRight[{}, #, 1]]^2] &, 46] (* Michael De Vlieger, Nov 18 2017, after Harvey P. Dale at A002477 *)

PARI

vector(45,n, numdiv((10^n\9)^2) ) \\ Edited by M. F. Hasler, Nov 18 2017

PARI

apply( A063750=n->numdiv((10^n\9)^2), [1..80]) \\ M. F. Hasler, Nov 18 2017

Formula

a(n) = A000005(A002477(n)) = d(((10^n-1)/9)^2). - M. F. Hasler, Nov 18 2017

a(n) = A048691(A000042(n)). - Amiram Eldar, Nov 19 2024

Extensions

Edited and offset corrected by M. F. Hasler, Nov 18 2017