A066458 Numbers n such that Sum_{d runs through digits of n} d^d = pi(n) (cf. A000720).

12, 22, 132, 34543, 612415, 27236725, 27236752, 311162281, 311163138, 327361548, 9237866583, 17499331217, 17499551725, 36475999489, 36475999498

Offset

1,1

Comments

Note that only two terms, namely 34543 & 17499331217 are primes. So we have: 34543=prime(3^3+4^4+5^5+4^4+3^3), 17499331217=prime(1^1+7^7+4^4+9^9+9^9+3^3+3^3+1^1+2^2+1^1+7^7) and there is no other such prime. - Farideh Firoozbakht, Sep 23 2005

Links

Table of n, a(n) for n=1..15.

C. Caldwell and G. L. Honaker, Jr., Is pi(6521)=6!+5!+2!+1! unique?

Example

a(3)=132 because there are exactly 1^1+3^3+2^2 (or 32) prime numbers less than or equal to 132.

Mathematica

Do[ If[ Apply[Plus, IntegerDigits[n]^IntegerDigits[n]] == PrimePi[n], Print[n]], {n, 1, 10^7} ]

Crossrefs

Cf. A105328, A105329.

Sequence in context: A298323 A299216 A227072 * A246342 A101104 A330212

Adjacent sequences: A066455 A066456 A066457 * A066459 A066460 A066461

Keyword

base,nonn,fini,full

Author

Jason Earls, Jan 02 2002

Extensions

More terms from Robert G. Wilson v, Jan 15 2002

Terms 27236725 onwards from Farideh Firoozbakht, Apr 21 2005 and Sep 17 2005

Sequence completed by Farideh Firoozbakht, Sep 23 2005

Status

approved