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

0,2

Comments

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

Links

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

Formula

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

Example

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.

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);

Crossrefs

Cf. A001359, A002822, A006512, A339625.

Sequence in context: A215897 A276673 A282815 * A105055 A108506 A129284

Adjacent sequences: A339627 A339628 A339629 * A339631 A339632 A339633

Keyword

nonn

Author

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

Status

approved