A113898 Numbers k such that the value pi(k), the number of primes <= k, can be obtained deleting some of the repeating adjacent digits of k.

1196, 11373, 22517, 33597, 44639, 55646, 60062, 61159, 62256, 63346, 63347, 64448, 64544, 64555, 64577, 64588, 64599, 64611, 64655, 64668, 64700, 64711, 64722, 64774, 64884, 64992, 65545, 65770, 65880, 65881, 65990, 66644, 67746, 68841

Offset

1,1

Comments

Largest value below 10^7 is given by pi(110486) = 10486.

Links

Table of n, a(n) for n=1..34.

Example

pi(64668) = 6468, pi(99551) = 9551.

Mathematica

lst = {}; p=0; While[p < 10^7, n=PrimePi[ ++p]; {sp, sn}=Split/@IntegerDigits@{p, n}; If[First/@sp==First/@sn && And@@GreaterEqual@@@Transpose[Length/@#&/@{sp, sn}], AppendTo[lst, p]]]; lst

Crossrefs

Cf. A000720, A114924, A080794.

Sequence in context: A251915 A166221 A096955 * A059401 A059402 A252000

Adjacent sequences: A113895 A113896 A113897 * A113899 A113900 A113901

Keyword

base,nonn

Author

Giovanni Resta, Jan 29 2006

Status

approved