A158214 Smallest palindromic prime made up of 0's and k 1's, where k = A007310(n), odd numbers not divisible by 3.

100111001, 110111011, 1110111110111, 10111101110111101, 100111111111111111001, 1111111111111111111, 11111111111111111111111, 10111111111101110111111111101, 1111110111111111111111110111111

Offset

2,1

Comments

Smallest palindromic prime with digit sum A007310(n) and using only 0's and 1's.

Links

Chai Wah Wu, Table of n, a(n) for n = 2..167

Prog

(Python)
from __future__ import division
from sympy.utilities.iterables import multiset_permutations
from sympy import isprime
A158214_list = []
for i in range(2, 101):
    if i % 6 == 1 or i % 6 == 5:
        i2 = i//2
        l = i2
        flag = True
        while flag:
            dlist = '0'*(l-i2) + '1'*i2
            for d in multiset_permutations(dlist):
                s = ''.join(d)
                n = int(s+'1'+s[::-1])
                if isprime(n):
                    A158214_list.append(n)
                    flag = False
                    break
            else:
                l += 1 # Chai Wah Wu, Dec 17 2015

Crossrefs

Cf. A020449.

Sequence in context: A017276 A017516 A017648 * A052096 A348810 A306502

Adjacent sequences: A158211 A158212 A158213 * A158215 A158216 A158217

Keyword

nonn,base

Author

Lekraj Beedassy, Mar 13 2009

Status

approved