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A048547
a(n) is the smallest value of m such that A002378(m), the m-th oblong number, contains exactly n 9's.
10
9, 31, 890, 2234, 14131, 30331, 173031, 969520, 9958890, 31617890, 360542549, 547631234, 3316547890, 17318486343, 114017542334, 356363452109, 3065925634968, 9995498986343, 44045425415132, 173193446755643, 1414213562370264, 4471015432706534, 31575306806579083, 171463720944111031, 141138230008594765
OFFSET
1,1
LINKS
Eric Weisstein's World of Mathematics, Pronic Number
EXAMPLE
From Jesse Sealand, Oct 07 2019: (Start)
a(1) = 9 since A002378(9) = 90;
a(2) = 31 since A002378(31) = 992;
a(3) = 890 since A002378(890) = 792990;
a(4) = 2234 since A002378(2234) = 4992990, etc.
(End).
KEYWORD
nonn,base
AUTHOR
Patrick De Geest, May 15 1999
EXTENSIONS
a(13)-a(16) from Lars Blomberg, Jun 10 2011
Name edited by Jesse Sealand, Oct 07 2019
a(17) from Giovanni Resta, Oct 09 2019
a(18)-a(25) from Max Alekseyev, Jul 25 2024
STATUS
approved