A116056 n and pi(n) are both made of nontrivial runs of identical digits, where pi(n)=A000720(n).

33, 8833, 66644, 66777, 117766, 118811, 990000, 1144000, 9997777, 115522333, 116660044, 116661111, 1100088555, 1100088855, 1100111100, 1100111111, 1100111333, 1100112200, 1100112211, 1100112222, 2277334444, 2277334455, 2277334466, 2277334477, 2277335500, 2288811222

Offset

1,1

Comments

A run of length 1 is trivial.

Up to 10^18 there are only 5 prime terms: 9997777, 1122991155533399, 44770077777722233, 440009996622997711, 442244499338866333. - Giovanni Resta, Sep 13 2019

Links

Giovanni Resta, Table of n, a(n) for n = 1..418 (terms < 10^18)

Example

pi(118811) = 11199, pi(9997777) = 664444.

Mathematica

zyQ[n_] := Min[Length /@ Split[IntegerDigits[n]]] > 1; Select[Range[10^7], zyQ[#] && zyQ[PrimePi[#]] &] (* Giovanni Resta, Sep 13 2019 *)

Crossrefs

Cf. A000720, A033023, A103357.

Sequence in context: A336261 A060705 A061687 * A337807 A232148 A229845

Adjacent sequences: A116053 A116054 A116055 * A116057 A116058 A116059

Keyword

nonn,base

Author

Giovanni Resta, Feb 13 2006

Extensions

More terms from Giovanni Resta, Sep 13 2019

Status

approved