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Search: id:A097639
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| A097639 |
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a(n) is the smallest number m such that for the n-digit number s=10^(n-1)+ m, 10*s+1, 10*s+3, 10*s+7 and 10*s+9 are primes. |
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2
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| 0, 0, 48, 300, 111, 234, 1395, 546, 2526, 5742, 753, 12369, 5658, 94572, 6744, 134649, 32523, 43071, 213927, 256116, 8172, 431904, 57138, 433125, 123225, 711447, 318501, 40758, 150063, 184602, 134661, 377778, 129048, 504678, 88113, 3174738
(list; graph; listen)
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OFFSET
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1,3
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COMMENT
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a(n)=A097638(n)-10^(n-1). a(50)= 10718757, can you find a(100)?
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FORMULA
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a[n_]:=(For[m=0, !(PrimeQ[10^n+10m+1]&&PrimeQ[10^n+10m+3]&&PrimeQ [10^n+10m+7]&&PrimeQ[10^n+10m+9]), m++ ];m);
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EXAMPLE
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a(4)=300 because 10(10^3+300)+ 1, 10(10^3+300)+ 3,10(10^3+300)+ 7 &
10(10^3+300)+1, are primes and 300 is the smallest number with
this property.
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MATHEMATICA
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a[n_]:=(For[m=0, !(PrimeQ[10^n+10m+1]&&PrimeQ[10^n+10m+3]&&PrimeQ[ 10^n+10m+7]&&PrimeQ[10^n+10m+9]), m++ ]; m); Table[a[n], {n, 43}]
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CROSSREFS
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Cf. A097638, A007811.
Sequence in context: A052683 A115056 A001337 this_sequence A134607 A037056 A110275
Adjacent sequences: A097636 A097637 A097638 this_sequence A097640 A097641 A097642
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KEYWORD
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base,nonn
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AUTHOR
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Farideh Firoozbakht (f.firoozbakht(AT)math.ui.ac.ir), Aug 18 2004
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