A330303 Least start of a run of exactly n consecutive odd numbers that are all de Polignac numbers (A006285).

1, 905, 18895, 56287, 3296885, 53892169, 496722329, 1415354159, 110690012639

Offset

1,2

Links

Table of n, a(n) for n=1..9.

Example

a(2) = 905 since both 905 and 905 + 2 = 907 are de Polignac numbers.
a(3) = 18895 since 18895, 18895 + 2 = 18897 and 18895 + 4 = 18899 are all de Polignac numbers.

Mathematica

dePolQ[n_] := AllTrue[n - 2^Range[0, Floor[Log[2, n]]], !PrimeQ[#] &]; max = 5; seq = Table[0, {max}]; count = 0; k = 3; While[count < max, If[dePolQ[k], kk = k + 2; While[dePolQ[kk], kk += 2]; n = (kk - k)/2; If[n <= max && seq[[n]] == 0, count++; seq[[n]] = k]; k = kk + 2, k += 2]]; seq

Crossrefs

Cf. A006285, A330284.

Sequence in context: A068856 A235949 A330284 * A181257 A235242 A270446

Adjacent sequences: A330300 A330301 A330302 * A330304 A330305 A330306

Keyword

nonn,more

Author

Amiram Eldar, Dec 13 2019

Status

approved