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A307473
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SanD-50 primes: primes p such that p+d is also prime and sum of digits A007953(p(p+d)) = d, with d = 50.
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3
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2543, 3137, 3407, 4973, 5147, 5693, 7193, 7523, 7649, 7673, 8243, 8513, 8573, 8627, 9293, 9461, 9497, 9767, 9833, 9857, 9923, 10463, 11279, 11777, 11789, 12107, 12161, 12647, 12917, 12953, 13043, 13127, 13217, 14033, 15137, 15443, 15767, 15773, 16061, 16427, 16553, 16607, 16937, 16943, 17117, 17207, 18047
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OFFSET
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1,1
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COMMENTS
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SanD-d primes exist only for d = 14 + 18*k, k = -1/2, 0, 1, 2, 3, ...
This is the sequence for k = 2. See cross-references for other k and related sequences, in particular the main entry A307479 with further references.
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LINKS
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EXAMPLE
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a(1) = 2543 = A307479(42) = A307480(2) is the smallest SanD-50 prime: 2543 and 2543 + 50 = 2593 both are prime, and the digit sum A007953(2543*2593) = 6+5+9+3+9+9+9 = 50.
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MAPLE
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sand:= (n, d) -> isprime(n) and isprime(n+d) and convert(convert(n*(n+d), base, 10), `+`)=d:
select(sand, [seq(i, i=5..20000, 6)], 50); # Robert Israel, Apr 10 2019
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PROG
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(PARI) print_A307473(N, d=50)=forprime(p=2, , isprime(p+d)&&sumdigits(p*(p+d))==d&&!print1(p, ", ")&&!N--&&break)
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CROSSREFS
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KEYWORD
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nonn,base
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AUTHOR
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STATUS
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approved
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