A165691 Primes p such that pi(p) is the product of the first digit of p and the rest of the number.

17, 73, 619, 2077121, 5070613, 503890508623

Offset

1,1

Comments

A subsequence of A112013. There is no further term up to 3*10^10.

a(7) > 2.07*10^12. - Giovanni Resta, Feb 27 2013

a(7) > 10^17. - Chai Wah Wu, Apr 15 2021

Links

Table of n, a(n) for n=1..6.

Example

619=prime(6*19), so 619 is in the sequence.

Mathematica

Do[If[h=IntegerDigits[Prime[m]]; m==h[[1]]*FromDigits[Delete[h, 1]],
Print[Prime[m]}]], {m, 355000}]

Crossrefs

Cf. A000040, A112013.

Sequence in context: A146658 A145440 A112013 * A154419 A208399 A097223

Adjacent sequences: A165688 A165689 A165690 * A165692 A165693 A165694

Keyword

hard,more,nonn,base

Author

Farideh Firoozbakht, Oct 14 2009

Extensions

a(6) from Giovanni Resta, Feb 27 2013

Status

approved