A064915 Positive integers n that are not of the form p + q * a^2, where p and q are primes and a is the smallest prime not dividing n.

1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 12, 14, 16, 18, 22, 24, 26, 28, 30, 36, 42, 48, 54, 60, 66, 72, 77, 84, 90, 96, 102, 108, 114, 120, 126, 174, 180, 210, 240, 270, 300, 330, 420, 630, 840, 1050, 1260

Offset

1,2

Comments

There are no other terms up to 10^7. Conjecture: There are no more terms in the sequence.

Links

Table of n, a(n) for n=1..47.

Mathematica

rep[ n_ ] := Module[ {a, q}, For[ a=2, GCD[ n, a ]!=1, a++, Null ]; For[ q=2, q a^2<n, q++, If[ PrimeQ[ q ]&&PrimeQ[ n-q a^2 ], Return[ True ] ] ]; False ]; Select[ Range[ 1, 10000 ], !rep[ # ]& ]

Crossrefs

Cf. A064653.

Sequence in context: A242367 A355596 A246077 * A375969 A180648 A322605

Adjacent sequences: A064912 A064913 A064914 * A064916 A064917 A064918

Keyword

nonn

Author

Dean Hickerson, Oct 13 2001

Status

approved