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A335498 a(n) is the least odd number k such that Omega(k) = n and Omega(k+2) = n+1, where Omega(k) is the number of prime factors of k (A001222). 0
1, 7, 25, 873, 1375, 41875, 903123, 1015623, 49671873, 200921875, 1157734375, 41898828123 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

LINKS

Table of n, a(n) for n=0..11.

EXAMPLE

a(3) = 873 because Omega(873) = Omega(3^2*97) = 3, Omega(873+2) = Omega(5^3*7) = 4 and 873 is the smallest such integer.

MATHEMATICA

a[n_] := Block[{ov=0, v=1, k=3}, While[ov != n || v != n+1, ov = v; k += 2; v = PrimeOmega@ k]; k-2]; a /@ Range[0, 6]

CROSSREFS

Cf. A001222, A322300, A335496.

Sequence in context: A318633 A300527 A214593 * A012490 A157702 A063453

Adjacent sequences:  A335495 A335496 A335497 * A335499 A335500 A335501

KEYWORD

nonn,more

AUTHOR

Giovanni Resta, Jun 11 2020

STATUS

approved

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Last modified September 30 11:55 EDT 2020. Contains 337439 sequences. (Running on oeis4.)