login
A048529
a(n) is the smallest value of m such that A002378(m), the m-th oblong number, contains exactly n 0's.
10
0, 24, 100, 624, 1000, 10001, 10000, 100001, 100000, 1000001, 1000000, 10000001, 10000000, 100000001, 100000000, 1000000001, 1000000000, 10000000001, 10000000000
OFFSET
1,2
LINKS
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 *)
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