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A049529 Numbers n such that sum of factorials of digits of n equals pi(n) (A000720). 3
6500, 6501, 6510, 6511, 6521, 12066, 50372, 175677, 553783, 5224903, 5224923, 5246963, 5302479, 5854093, 5854409, 5854419, 5854429, 5854493, 5855904, 5864049, 5865393, 10990544, 11071599 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

By the time that n = 10^8 the number of primes <= 10^8 (5761455) exceeds 8*9! (2903040). - Robert G. Wilson v, Jan 16 2002

LINKS

Table of n, a(n) for n=1..23.

C. Caldwell and G. L. Honaker, Jr., Is pi(6521)=6!+5!+2!+1! unique?, Math. Spectrum, 22:2 (2000/2001) 34-36.

G. L. Honaker, Jr. and Chris Caldwell, Prime Curios! 6521

Eric Weisstein's World of Mathematics, Factorial

EXAMPLE

a(10)=5224903 because there are exactly 5!+2!+2!+4!+9!+0!+3! (or 363035) prime numbers less than or equal to 5224903.

MATHEMATICA

Do[ If[ Apply[ Plus, IntegerDigits[n] ! ] == PrimePi[n], Print[n]], {n, 1, 11100000} ]

CROSSREFS

Cf. A000720, A049530.

Sequence in context: A031842 A028544 A237245 * A284102 A251447 A156416

Adjacent sequences:  A049526 A049527 A049528 * A049530 A049531 A049532

KEYWORD

fini,full,nonn,base

AUTHOR

G. L. Honaker, Jr., Sep 15 1999.

STATUS

approved

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Last modified June 26 23:21 EDT 2017. Contains 288777 sequences.