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A158571
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Primes whose digit sum is a single-digit nonprime.
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1
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13, 17, 31, 53, 71, 103, 107, 211, 233, 251, 431, 503, 521, 701, 1021, 1061, 1151, 1201, 1223, 1511, 1601, 2011, 2141, 2213, 2411, 3001, 3023, 3041, 3203, 3221, 4013, 4211, 5003, 5021, 6011, 6101, 7001, 10007, 10061, 10111, 10133, 10151, 10223, 10313
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OFFSET
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1,1
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COMMENTS
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It is interesting to observe that it is hard to find (I found none) primes whose digit sum is 6. On the contrary, it is easier to find primes whose digit sum is 8.
The digit sum 6 does not occur here because a number with digit sum 6 is divisible by 3 and therefore not prime. - R. J. Mathar, Mar 26 2009
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LINKS
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FORMULA
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EXAMPLE
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1061 is a prime whose digit sum is 8, which is a single-digit nonprime.
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MAPLE
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for i from 1 to 8 do if member(i, [1, 3, 7]) then S[1, i]:= {i} else S[1, i]:= {} fi od:
for d from 2 to 5 do
for x from 1 to 8 do
S[d, x]:= {};
for y from 0 to x-1 do
S[d, x]:= S[d, x] union map(t -> 10^(d-1)*y + t, S[d-1, x-y])
od od od:
select(isprime, S[5, 4] union S[5, 8]); # Robert Israel, Apr 14 2021
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CROSSREFS
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KEYWORD
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base,nonn
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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