[go: up one dir, main page]

login
A116054
n times pi(n) is a palindrome, where pi(n) = PrimePi(n) = A000720(n).
1
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
OFFSET
1,2
LINKS
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
Sequence in context: A301877 A369438 A221172 * A339782 A176621 A370365
KEYWORD
nonn,base
AUTHOR
Giovanni Resta, Feb 13 2006
STATUS
approved