A339630 a(n) is the first number k such that there are exactly n ways to write 6*k = p + q with p a lesser twin prime (A001359) and q a greater twin prime (A006512), or 0 if there is no such k.

1, 2, 3, 4, 8, 20, 19, 80, 40, 90, 48, 270, 35, 50, 117, 140, 110, 644, 215, 714, 222, 430, 345, 350, 315, 850, 390, 930, 620, 1110, 602, 1040, 385, 2290, 590, 780, 798, 910, 735, 990, 1020, 1700, 700, 770, 595, 1760, 950, 3380, 875, 5660, 1330, 1120, 975, 5970, 1085, 2990, 1400, 3980, 1815, 4570

Offset: 0

Author

J. M. Bergot and Robert Israel, Dec 10 2020

Keywords

• nonn

Comments

If n is odd, a(n)/2 (if nonzero) is in A002822.

Examples

			a(4) = 8 because 6*8 = 48 can be written as p+q in exactly 4 ways: 48 = 5 + 43 = 17 + 31 = 29 + 19 = 41 + 7, and no smaller number has this property.
		

Links

• Robert Israel, Table of n, a(n) for n = 0..1330

Crossrefs

Cf. A001359, A002822, A006512, A339625.

Programs

Maple

# given list A339625
T:= Array(0..max(A339625)):
for n from 1 to nops(A339625) do
  if T[A339625[n]] = 0 then T[A339625[n]]:= n fi
od:
for k from 1 while T[k] <> 0 do od:
seq(T[i],i=0..k-1);

Formula

A339625(a(n)) = n if a(n) > 0.