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A061597
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Product of digits + 1 is prime, product of digits - 1 is prime, sum of digits + 1 is prime, sum of digits - 1 is prime and product of digits = sum of digits.
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1
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4, 6, 22, 123, 132, 213, 231, 312, 321, 111126, 111162, 111216, 111261, 111612, 111621, 112116, 112161, 112611, 116112, 116121, 116211, 121116, 121161, 121611, 126111, 161112, 161121, 161211, 162111, 211116, 211161, 211611, 216111, 261111, 611112
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OFFSET
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1,1
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LINKS
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EXAMPLE
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22 belong to the sequence because (2*2)+1=5, (2*2)-1=3, (2+2)+1=5, (2+2)-1=3 and 2+2=2*2.
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PROG
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(PARI) SumD(x)= s=0; while (x>9, s=s+x-10*(x\10); x=x\10); s + x
ProdD(x)=p=1; while (x>9, p=p*(x-10*(x\10)); x=x\10); p*x
x=9; for (n=0, 78, until(s==p && isprime(s+1) && isprime(s-1) && isprime(p+1) && isprime(p-1), x++; s=SumD(x); p=ProdD(x)); write("b061597.txt", n, " ", x)) \\ Harry J. Smith, Jul 25 2009; does not produce the terms 4 and 6
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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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EXTENSIONS
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4 and 6 added by Abdul Gaffar Khan, Nov 29 2015
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STATUS
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approved
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