A211389 a(n) is the first occurrence of n in sequence A209266.

3, 5, 9, 14, 16, 26, 54, 67, 74, 103, 161, 293, 236, 432, 249, 788, 1078, 796, 1885, 2091, 1712, 2618, 4099, 7088, 8137, 8091, 16086, 12595, 27627, 22835, 44576, 31305, 68888, 109617, 86463, 77206, 126383, 202035

Offset

1,1

Links

Table of n, a(n) for n=1..38.

Example

A209266 = {0, 0, 1, 1, 2, 2, 2, 1, 3, 3, 1, 3, 3, 4, 3, 5, 4, 2, 5, 4, 4, 4, 4, 3, 3, 6, 6, 4,...}.
Number 1 first appears as A209266(3), number 2 as A209266(5), number 3 as A209266(9)...
So, a = {3, 5, 9, ...} starting from a(1)=3.

Mathematica

aim = 32; a = Table[0, {i, 1, aim}]; zeros = aim; i = 2; While[i++; p = Prime[i]; ct = 0; Do[If[(PrimeQ[p - j]) && (PrimeQ[p + j]), f = Last[FactorInteger[j]][[1]]; If[f <= 5, ct++]], {j, 2, p, 2}]; If[(ct <= aim) && (a[[ct]] == 0), a[[ct]] = i; zeros--; zeros > 0]; a

Crossrefs

Cf. A209266.

Sequence in context: A146433 A134672 A321024 * A335193 A288259 A355489

Adjacent sequences: A211386 A211387 A211388 * A211390 A211391 A211392

Keyword

nonn,hard

Author

Lei Zhou, Feb 07 2013

Status

approved