

A239237


Numbers n such that n^d_1 + n^d_2 + ... n^d_k is prime where d_i is the ith digit in the decimal representation of n.


2



10, 20, 203, 230, 308, 309, 330, 350, 503, 603, 650, 960, 1068, 1110, 1206, 1350, 1404, 1480, 1730, 1802, 1860, 1910, 2032, 2038, 2044, 2054, 2250, 2320, 2502, 3044, 3082, 3402, 3970, 4032, 4046, 4072, 4120, 4340, 4450, 4540, 4650, 4908, 5204, 5310, 5402
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OFFSET

1,1


COMMENTS

The number must contain a 0 in its decimal representation. If not, the number is divisible by n.


LINKS

Giovanni Resta, Table of n, a(n) for n = 1..10000


EXAMPLE

20^2 + 20^0 = 401 is prime so 20 is a member of this sequence.
308^3 + 308^0 + 308^8 = 80985213602898040129 is prime so 308 is a member of this sequence.


MATHEMATICA

Select[Range[5000], PrimeQ@ Total[#^IntegerDigits[#]] &] (* Giovanni Resta, Mar 13 2014 *)


PROG

(Python)
import sympy
from sympy import isprime
def PowOpp(x):
..if str(x).find('0') > 1:
....num = 0
....for i in str(x):
......num += x**int(i)
....if isprime(num):
......return True
x = 1
while x < 10**4:
..if PowOpp(x):
....print(x)
..x += 1


CROSSREFS

Cf. A239236.
Subsequence of A011540.
Sequence in context: A250107 A217318 A038693 * A018990 A280882 A335802
Adjacent sequences: A239234 A239235 A239236 * A239238 A239239 A239240


KEYWORD

nonn,base


AUTHOR

Derek Orr, Mar 13 2014


STATUS

approved



