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A239237 Numbers n such that n^d_1 + n^d_2 + ... n^d_k is prime where d_i is the i-th 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 (list; graph; refs; listen; history; text; internal format)
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

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Last modified July 9 16:50 EDT 2020. Contains 335545 sequences. (Running on oeis4.)