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A225864 Composite numbers for which both sum and product of digits are primes. 1
12, 21, 115, 511, 1112, 1121, 1211, 11711, 13111, 17111, 31111, 71111, 111112, 121111, 211111, 1111115, 1111117, 1111171, 1111511, 1115111, 1151111, 1511111, 1711111, 5111111, 7111111, 111111115, 111111151, 111111311, 111111511, 111115111, 111131111, 111151111 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Chai Wah Wu, Table of n, a(n) for n = 1..10000

MATHEMATICA

d[n_] := IntegerDigits[n]; t={}; Do[If[!PrimeQ[n] && PrimeQ[Plus@@(x=d[n])] && PrimeQ[Times@@x], AppendTo[t, n]], {n, 2*10^6}]; t

PROG

(Python)

from __future__ import division

from sympy import isprime

A225864_list = []

for l in range(1, 20):

    plist, q = [p for p in [2, 3, 5, 7] if isprime(l-1+p)], (10**l-1)//9

    for i in range(l):

        for p in plist:

            r = q+(p-1)*10**i

            if not isprime(r):

                A225864_list.append(r) # Chai Wah Wu, Aug 15 2017

CROSSREFS

Cf. A046713, A225863.

Sequence in context: A201015 A044005 A321771 * A134514 A030299 A268532

Adjacent sequences:  A225861 A225862 A225863 * A225865 A225866 A225867

KEYWORD

nonn,base

AUTHOR

Jayanta Basu, May 18 2013

EXTENSIONS

Extended by T. D. Noe, May 18 2013

STATUS

approved

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Last modified April 5 13:33 EDT 2020. Contains 333241 sequences. (Running on oeis4.)