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A342259
Numbers k such that omega(k-1) = omega(k)-1 and omega(k+1) = omega(k)+1, where omega(m) is the number of distinct primes dividing m, A001221(m).
2
65, 104, 129, 164, 194, 272, 284, 314, 344, 384, 398, 464, 524, 608, 614, 626, 662, 692, 734, 758, 824, 968, 1025, 1094, 1172, 1238, 1280, 1304, 1364, 1424, 1448, 1454, 1532, 1544, 1595, 1658, 1664, 1682, 1724, 1754, 1832, 1868, 1869, 1934, 1952, 2000, 2001, 2012
OFFSET
1,1
LINKS
EXAMPLE
a(1)=65: 64=2^6 (1 distinct prime 2), 65=5*13 (2 distinct primes 5 and 13, 66=2*3*11 (3 distinct primes 2, 3, and 11).
MATHEMATICA
seq[nmax_] := Module[{om}, om[n_] := om[n] = PrimeNu[n]; Select[Range[2, nmax], om[# - 1] == om[#] - 1 && om[# + 1] == om[#] + 1 &]]; seq[2500] (* Amiram Eldar, Sep 19 2024 *)
PROG
(PARI) for(n=3, 2100, my(om=omega(n)); if(omega(n-1)==om-1&&omega(n+1)==om+1, print1(n, ", ")))
CROSSREFS
Sequence in context: A299456 A300094 A350241 * A075893 A064901 A039482
KEYWORD
nonn
AUTHOR
Hugo Pfoertner, Mar 07 2021
STATUS
approved