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A353300 Numbers k such that A004394(k)-1 is prime. 3
3, 4, 5, 6, 8, 9, 11, 12, 13, 14, 15, 16, 19, 20, 24, 25, 26, 30, 32, 41, 47, 48, 49, 51, 57, 59, 76, 82, 83, 92, 104, 105, 117, 119, 131, 134, 137, 139, 143, 154, 166, 170, 172, 180, 209, 214, 215, 216, 217, 227, 231, 234, 247, 265, 269, 271, 284, 317, 327, 348 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,1
COMMENTS
First differs from A306588 at n=15.
LINKS
EXAMPLE
3 is a term since A004394(3)-1 = 4-1 = 3 is prime.
MATHEMATICA
s = {}; abm = 0; k = 0; Do[ab = DivisorSigma[-1, n]; If[ab > abm, abm = ab; k++; If[PrimeQ[n - 1], AppendTo[s, k]]], {n, 1, 10^6}]; s
CROSSREFS
Sequence in context: A359168 A332739 A306588 * A219636 A047428 A218784
KEYWORD
nonn
AUTHOR
Amiram Eldar, Apr 10 2022
STATUS
approved

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Last modified July 15 21:59 EDT 2024. Contains 374334 sequences. (Running on oeis4.)