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A090118 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. 4
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 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Table of n, a(n) for n=1..36.

FORMULA

a(n)=prevprime[A090116(n)^2]-prevprime[A090117(n)]=p[pi[A090117(n)]]

EXAMPLE

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.

MATHEMATICA

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]}]

CROSSREFS

Cf. A090116-A090119.

Sequence in context: A090188 A001773 A067604 * A099183 A316792 A110864

Adjacent sequences:  A090115 A090116 A090117 * A090119 A090120 A090121

KEYWORD

nonn

AUTHOR

Labos Elemer, Jan 09 2004

STATUS

approved

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Last modified June 4 10:04 EDT 2020. Contains 334825 sequences. (Running on oeis4.)