

A285689


a(1) = 2; a(n + 1) = smallest prime > a(n) such that a(n + 1)  a(n) is the product of four primes.


6



2, 83, 107, 131, 167, 191, 227, 251, 307, 331, 347, 383, 419, 443, 467, 491, 547, 563, 587, 641, 677, 701, 757, 773, 797, 821, 857, 881, 937, 953, 977, 1013, 1049, 1103, 1163, 1187, 1223, 1259, 1283, 1307, 1361, 1451, 1487, 1511, 1567, 1583, 1607, 1663, 1699, 1723, 1747, 1783, 1823
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OFFSET

1,1


COMMENTS

First differences: 81, 24, 24, 36, 24, 36, 24, 56, 24, 16, 36, 36, 24, 24, 24, 56, 16, 24, 54, 36, 24,...


LINKS

Robert Israel, Table of n, a(n) for n = 1..10000


MAPLE

A[1]:= 2: p:= 2: n:= 1:
while n < 60 do
p:= nextprime(p);
if numtheory:bigomega(pA[n]) = 4 then n:= n+1; A[n]:= p; fi
od:
seq(A[i], i=1..60); # Robert Israel, Nov 28 2019


MATHEMATICA

NestList[Module[{p = NextPrime@ #}, While[PrimeOmega[p  #] != 4, p = NextPrime@ p]; p] &, 2, 52] (* Michael De Vlieger, Apr 25 2017 *)


CROSSREFS

Cf. A255609, A285688.
Sequence in context: A087617 A263365 A140157 * A139867 A260674 A090434
Adjacent sequences: A285686 A285687 A285688 * A285690 A285691 A285692


KEYWORD

nonn,changed


AUTHOR

Zak Seidov, Apr 24 2017


STATUS

approved



