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A022761

n-th 8k+1 prime plus n-th 8k+7 prime.

24, 64, 104, 136, 168, 192, 240, 320, 384, 408, 448, 480, 536, 576, 616, 672, 720, 792, 816, 840, 952, 1008, 1040, 1072, 1088, 1120, 1240, 1280, 1392, 1416, 1528, 1584, 1624, 1680, 1760, 1792, 1840, 1896, 1944, 1968, 2064, 2112, 2144, 2224

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OFFSET

1,1

LINKS

Harvey P. Dale, Table of n, a(n) for n = 1..1000

EXAMPLE

The first four primes of the form 8k - 1 are 7, 23, 31, 47. The first four primes of the form 8k + 1 are 17, 41, 73, 89.

Thus a(1) = 7 + 17 = 24.

a(2) = 23 + 41 = 64.

a(3) = 31 + 73 = 104.

a(4) = 47 + 89 = 136.

MATHEMATICA

thresh = 100; A007522 = Select[8Range[thresh] - 1, PrimeQ]; A007519 = Select[8Range[thresh] + 1, PrimeQ]; preExh = Min[Length[A007522], Length[A007519]]; Take[A007522, preExh] + Take[A007519, preExh]

Module[{nn=300, p1, p7, len}, p1=Select[Prime[Range[nn]], IntegerQ[(#-1)/8]&]; p7=Select[Prime[Range[nn]], IntegerQ[(#-7)/8]&]; len=Min[ Length[ p1], Length[ p7]]; Total/@Thread[{Take[p1, len], Take[p7, len]}]] (* Harvey P. Dale, May 26 2020 *)

CROSSREFS

Cf. A007522, A007519.

Sequence in context: A371174 A045558 A352343 * A090386 A239596 A306132

Adjacent sequences: A022758 A022759 A022760 * A022762 A022763 A022764

KEYWORD

nonn

AUTHOR

Clark Kimberling

STATUS

approved

URL: https://oeis.org/A022761

⇱ A022761 - OEIS