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A157485 Numbers k such that k-+1 are divisible by exactly 5 primes, counted with multiplicity. 4
271, 593, 701, 751, 919, 1169, 1241, 1639, 1649, 1673, 1711, 1751, 2071, 2311, 2393, 2549, 2551, 2609, 2729, 2861, 2863, 2897, 2899, 3185, 3331, 3569, 3631, 3823, 3849, 3851, 3943, 3977, 4231, 4265, 4649, 4663, 5071, 5081, 5237, 5239, 5391, 5551, 5561, 5585, 5741 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Jinyuan Wang, Table of n, a(n) for n = 1..5000

MATHEMATICA

q=5; lst={}; Do[If[Plus@@Last/@FactorInteger[n-1]==q&&Plus@@Last/@FactorInteger[n+1]==q, AppendTo[lst, n]], {n, 7!}]; lst

Select[Range[6000], PrimeOmega[#+{1, -1}]=={5, 5}&] (* Harvey P. Dale, Jun 05 2021 *)

PROG

(PARI) is(k) = bigomega(k-1)==5 && bigomega(k+1)==5; \\ Jinyuan Wang, Mar 22 2020

CROSSREFS

Cf. A014612, A124936, A157483, A157484.

Sequence in context: A142637 A288881 A245969 * A038655 A108835 A185668

Adjacent sequences:  A157482 A157483 A157484 * A157486 A157487 A157488

KEYWORD

nonn

AUTHOR

Vladimir Joseph Stephan Orlovsky, Mar 01 2009

EXTENSIONS

More terms from Jinyuan Wang, Mar 22 2020

STATUS

approved

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Last modified July 29 05:59 EDT 2021. Contains 346340 sequences. (Running on oeis4.)