A048529 a(n) is the smallest value of m such that A002378(m), the m-th oblong number, contains exactly n 0's.

0, 24, 100, 624, 1000, 10001, 10000, 100001, 100000, 1000001, 1000000, 10000001, 10000000, 100000001, 100000000, 1000000001, 1000000000, 10000000001, 10000000000

Offset

1,2

Links

Table of n, a(n) for n=1..19.

Eric Weisstein's World of Mathematics, Pronic Number

Example

From Jesse Sealand, Oct 05 2019: (Start)
a(1) = 0 since A002378(0) = 0;
a(2) = 24 since A002378(24) = 600;
a(3) = 100 since A002378(100) = 10100;
a(4) = 624 since A002378(624) = 390000, etc.
(End).

Mathematica

a[n_] := Block[{a = 0}, While[Count[IntegerDigits[a*(a + 1)], 0] != n, ++a]; Return[a]]; a /@ Range[1, 10] (* Julien Kluge, Dec 15 2016 *)

Crossrefs

Cf. A002378, A048530.

Cf. A048531, A048533, A048535, A048537, A048539, A048541, A048543, A048545, A048547.

Sequence in context: A100152 A233405 A297798 * A213842 A333033 A269047

Adjacent sequences: A048526 A048527 A048528 * A048530 A048531 A048532

Keyword

nonn,base,more

Author

Patrick De Geest, May 15 1999

Extensions

a(16)-a(19) from Lars Blomberg, Jun 10 2011

Name edited by Jesse Sealand, Oct 05 2019

Status

approved