Voozh

A116054

n times pi(n) is a palindrome, where pi(n) = PrimePi(n) = A000720(n).

1, 2, 3, 4, 11, 28, 33, 37, 44, 53, 132, 138, 279, 378, 458, 474, 482, 504, 674, 1628, 1696, 2002, 2332, 3117, 4183, 5518, 6341, 6623, 7094, 19261, 25971, 28402, 28831, 33827, 39119, 51387, 65621, 85997, 87843, 174944, 178926, 212212, 258357

(list; graph; refs; listen; history; text; internal format)

OFFSET

1,2

LINKS

Chai Wah Wu, Table of n, a(n) for n = 1..100

EXAMPLE

85997 * p(85997) = 719020917.

MATHEMATICA

ntpQ[n_]:=Module[{idn=IntegerDigits[n*PrimePi[n]]}, idn==Reverse[idn]]; Select[Range[300000], ntpQ] (* Harvey P. Dale, Nov 13 2013 *)

PROG

(Python)

from sympy import nextprime

n, k, m, A116054_list = 0, 1, 2, []

while len(A116054_list) < 100:

for i in range(k, m):

s = str(i*n)

if s == s[::-1]:

A116054_list.append(i)

n += 1

k, m = m, nextprime(m) # Chai Wah Wu, Jul 25 2018

CROSSREFS

Cf. A000720, A116053.

Sequence in context: A301877 A369438 A221172 * A339782 A176621 A370365

Adjacent sequences: A116051 A116052 A116053 * A116055 A116056 A116057

KEYWORD

nonn,base

AUTHOR

Giovanni Resta, Feb 13 2006

STATUS

approved

URL: https://oeis.org/A116054

⇱ A116054 - OEIS