A114924 Primes p such that pi(p) is obtained by dropping one of the digits of p in decimal expansion.

17, 12491, 14723, 42437, 57089, 58193, 61051, 63131, 63347, 64553, 64567, 64577, 64591, 64601, 64661, 64679, 64951, 65071, 65173, 65293, 65881, 66863, 69931, 79817, 99551, 129083, 165103, 263071, 284833, 1407647, 1515259, 4303027

Offset: 1

Author

Farideh Firoozbakht, Jan 14 2006

Keywords

• fini
• base
• nonn

Comments

If n>31 then we can get pi(a(n)) by dropping the first digit of a(n). Next term is greater than prime(20000000).

Examples

			95517973 is in the sequence because 95517973 is prime and pi(95517973)=5517973.
		

Crossrefs

Cf. A114924.

Programs

Mathematica

Do[h=IntegerDigits[Prime@n]; l=Length[h]; If[MemberQ[Table[ FromDigits[Drop[h, {k}]], {k, l}], n], Print[Prime@n]], {n, 20000000}]
prpiQ[n_]:=MemberQ[FromDigits/@Table[Drop[IntegerDigits[n],{d}],{d,IntegerLength[n]}],PrimePi[n]]; Select[Prime[Range[310000]],prpiQ] (* Harvey P. Dale, Dec 29 2024 *)