Puzzle 1256 Another sequence of primes
On Jan
6, 2026, Palolo sent this nice puzzle.
Consider the following process: take a prime k>9,
sum the digits, repeat the sum deleting the first
addendum and adding the previous sum and so on.
Sequence lists the minimum prime k that produces a
run of exactly n consecutive primes. (this sequence
is not yet present in OEIS)
I've found the first 10 terms:
0 [13]
1 [23, 5]
2 [101,
2, 3]
3 [11, 2, 3, 5]
4 [317, 11, 19, 37, 67]
5
[331, 7, 11, 19, 37, 67]
6 [599,
23, 41, 73, 137, 251, 461]
7
[35311, 13, 23, 41, 79, 157, 313, 613]
8 [3393311, 23, 43, 83, 157, 311, 619,
1237, 2473]
9 [3533377, 31, 59,
113, 223, 443, 883, 1759, 3511, 6991]
10 [1933537, 31, 61, 113, 223, 443, 881,
1759, 3511, 6991, 13921]
11 [331733953, 37, 71, 139, 277, 547, 1091, 2179,
4349, 8693, 17383, 34729]
Example:
k(5) = 331 because:
1) 3 + 3 + 1 = 7, prime;
2) 3 + 1 + 7 = 11, prime;
3) 1 + 7 + 11 =
19, prime;
4) 7 + 11 + 19 = 37, prime;
5) 11 +
19 + 37 = 67, prime, and 19 + 37 + 67 = 123
composite.
Q.
Can you extend this sequence?
Last hour
news: Less than a couple of hours
after publishing this puzzle I received an email
from Michael Branicky, who wrote:
"This is
now in the OEIS as https://oeis.org/A391445
.
I have
already found and published the next (12th) term
there. It is:
12 [59393313971, 53, 101, 193, 383, 757,
1511, 3019, 6037, 12071, 24133, 48259, 96517]"