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

1,2

Links

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

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

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 *)

Prog

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

Crossrefs

Cf. A000005, A000042, A002477, A048691.

Sequence in context: A100401 A004166 A110759 * A143225 A223195 A203600

Adjacent sequences: A063747 A063748 A063749 * A063751 A063752 A063753

Keyword

nonn

Author

Jason Earls, Aug 11 2001

Extensions

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

Status

approved