A129314 Records in A127356.

1, 2, 6, 12, 24, 30, 42, 54, 60, 66, 90, 132, 138, 210, 270, 300, 318, 342, 390, 420, 450, 624, 690, 696, 750, 798, 924, 930, 1170, 1224, 1326, 1362, 1428, 1434, 1500

Offset

1,2

Links

Table of n, a(n) for n=1..35.

Example

As can be gathered from A127356, the first six records are A127356(1) = 1, A127356(2) = 2, A127356(3) = 6, A127356(10) = 12, A127356(13) = 24, A127356(77) = 30. Hence a(1) to a(6) are 1, 2, 6, 12, 24, 30.

Mathematica

sk[n_]:=Module[{k=2}, While[!PrimeQ[n+k^2], k=k+2]; k]; DeleteDuplicates[ Join[ {1}, Table[sk[n], {n, Prime[Range[2, 1000000]]}]], GreaterEqual] (* The program generates the first 22 terms of the sequence. *) (* Harvey P. Dale, Nov 07 2022 *)

Prog

(Python)
from itertools import count, islice
from sympy import isprime, nextprime, prime
def agen():
    pn = 2; record = 1; yield record
    for n in count(2):
        k, pn = 2, nextprime(pn)
        while not isprime(pn + k*k): k += 2
        if k > record: record = k; yield record
print(list(islice(agen(), 20))) # Michael S. Branicky, Nov 11 2022

Crossrefs

Cf. A127356, A129315 (where records occur).

Sequence in context: A307740 A244043 A058868 * A137895 A194096 A099993

Adjacent sequences: A129311 A129312 A129313 * A129315 A129316 A129317

Keyword

nonn,more

Author

Klaus Brockhaus, Apr 09 2007

Extensions

a(27)-a(33) from Donovan Johnson, Dec 09 2008

a(34)-a(35) from Michael S. Branicky, Nov 11 2022

Status

approved