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A087434 Number of brilliant numbers whose prime factors each have n digits. 3
10, 231, 10296, 563391, 34974066, 2374052871, 171745762321, 12989075028126, 1016377282340160, 81690831917887753, 6708792934060150753, 560785267822390134615, 47573053155260626453431 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Number of brilliant numbers having 2n or 2n-1 digits.

LINKS

Charles R Greathouse IV, Table of n, a(n) for n = 1..24

FORMULA

a(n)=A000217(A006879(n)).

PROG

(PARI) a(n)=binomial(primepi(10^n)-primepi(10^(n-1))+1, 2)

\\ Charles R Greathouse IV, May 03 2012

CROSSREFS

Cf. A006879, A006880, A078972, A086846, A087435.

Sequence in context: A056602 A239772 A239773 * A297648 A012240 A295410

Adjacent sequences:  A087431 A087432 A087433 * A087435 A087436 A087437

KEYWORD

nonn,base

AUTHOR

Ray Chandler, Sep 02 2003

EXTENSIONS

a(14) from Ray Chandler, Jul 21 2005

STATUS

approved

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Last modified October 16 03:37 EDT 2019. Contains 328040 sequences. (Running on oeis4.)