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Search: id:A097638
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| A097638 |
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a(n) is the smallest n-digit number m such that 10*m+1, 10*m+3, 10*m+7 & 10*m+9 are primes. |
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2
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| 1, 10, 148, 1300, 10111, 100234, 1001395, 10000546, 100002526, 1000005742, 10000000753, 100000012369, 1000000005658, 10000000094572, 100000000006744, 1000000000134649, 10000000000032523, 100000000000043071
(list; graph; listen)
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OFFSET
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1,2
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COMMENT
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a(n) is the smallest n-digit term of A007811. a(50)=10^49+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++ ];10^(n-1)+m);
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EXAMPLE
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a(4)=1300 because 13001,13003,13007 & 13009 are primes and 1300 is the
smallest 4-digit 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++ ]; 10^(n-1)+m); Table[a[n], {n, 28}]
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CROSSREFS
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Cf. A097639, A007811.
Sequence in context: A134526 A055761 A095889 this_sequence A098270 A116156 A025750
Adjacent sequences: A097635 A097636 A097637 this_sequence A097639 A097640 A097641
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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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