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Search: id:A090118
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| A090118 |
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a(n)=prevprime[A090116(n)], the largest prime previous to squares given in A090116, being such that distance of a(n) to the following prime equals 2n. |
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+0
2
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| 3, 7, 23, 359, 139, 619, 113, 1933, 523, 887, 3229, 1669, 2477, 10399, 5749, 10799, 9973, 22193, 30593, 25261, 121081, 76163, 93001, 157579, 212507, 35677, 118973, 1121453, 190921, 672379, 693881, 1003963, 259033, 1646033, 675643, 1207769
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OFFSET
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1,1
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FORMULA
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a(n)=prevprime[A090116(n)^2]-prevprime[A090117(n)]=p[pi[A090117(n)]]
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EXAMPLE
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n=7: a(7)=113 because 127-113=14=2.7 and 121=11 is
between {127,113} closest primes; also 113 is
the smallest prime with this property.
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MATHEMATICA
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pre[x_ := Prime[PrimePi[x]] nex[x_ := Prime[PrimePi[x]+1] de[x_ := Prime[PrimePi[x]+1]-Prime[PrimePi[x]] t=Table[de[w^2], {w, 1, 50000}]; mt=Table[Min[Flatten[Position[t, 2*j]]], {j, 1, 100}] Table[pre[Part[mt, j]^2], {j, 1, Length[mt]}]
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CROSSREFS
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Cf. A090116-A090119.
Sequence in context: A090188 A001773 A067604 this_sequence A099183 A110864 A046102
Adjacent sequences: A090115 A090116 A090117 this_sequence A090119 A090120 A090121
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KEYWORD
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nonn
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AUTHOR
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Labos E. (labos(AT)ana.sote.hu), Jan 09 2004
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