A048547 - OEIS

A048547

a(n) is the smallest value of m such that A002378(m), the m-th oblong number, contains exactly n 9's.

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

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OFFSET

1,1

LINKS

Table of n, a(n) for n=1..25.

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.