A020498 -id:A020498 - cp's OEIS frontend

A088649 Duplicate of A020498.

Original entry on oeis.org

1, 3, 7, 9, 13, 19, 21, 27, 31, 33, 37, 43, 49, 51, 57, 63, 69, 73, 79, 87, 91, 97, 99, 103

Offset: 1

dead

A088650 a(n) is the smallest x such that A020498(k) + x is prime for all k = 1 to n.

Original entry on oeis.org

1, 2, 4, 4, 4, 4, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10

Offset: 1

Amarnath Murthy, Oct 29 2003

Is the sequence finite?

			a(4)= 4 and the primes arising are 5, 7, 11, and 13.

Cf. A020498.

Corrected and extended by Max Alekseyev, Aug 23 2013

A141544 Odd numbers k such that 2k+5 is a prime.

Original entry on oeis.org

1, 3, 7, 9, 13, 19, 21, 27, 31, 33, 37, 39, 49, 51, 61, 63, 67, 73, 79, 81, 87, 93, 97, 103, 109, 111, 117, 123, 129, 133, 139, 151, 153, 163, 171, 177, 181, 187, 189, 207, 213, 217, 219, 229, 231, 237, 241, 243, 247, 249, 259, 271, 279, 283, 291, 297, 301, 307

Offset: 1

Giovanni Teofilatto, Aug 16 2008

nonn

Superset of A107771. The corresponding primes are given by deleting the first entry in A002145. - R. J. Mathar, Aug 18 2008

Cf. A002145, A020498, A087915, A089038, A090670, A107771.

a:=proc(n) if isprime(2*n+5) then n end if end proc: seq(a(2*n-1), n=1..170); # Emeric Deutsch, Aug 17 2008

Select[Range[1,307,2],PrimeQ[2#+5]&] (* James C. McMahon, Jul 26 2025 *)

A089038 INTERSECT A005408. - R. J. Mathar, Aug 18 2008

a(n) = A087915(n+1) - 1 = A090670(n+1) - 4. - Giovanni Teofilatto, Sep 07 2008

Extended by Emeric Deutsch, Aug 17 2008 and R. J. Mathar, Aug 18 2008

cp's OEIS Frontend

A088649 Duplicate of A020498.

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A088650 a(n) is the smallest x such that A020498(k) + x is prime for all k = 1 to n.

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A141544 Odd numbers k such that 2k+5 is a prime.

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