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 A104377 Number of distinct prime divisors of numbers derived from three consecutive concatenated odd numbers. 2
 2, 3, 2, 2, 3, 4, 2, 3, 3, 2, 4, 2, 2, 2, 2, 4, 3, 3, 2, 2, 4, 3, 3, 3, 2, 5, 3, 2, 3, 3, 3, 3, 2, 2, 2, 3, 2, 3, 3, 3, 3, 3, 3, 3, 2, 3, 3, 3, 4, 2, 4, 4, 4, 3, 3, 4, 2, 3, 4, 3, 4, 3, 3, 3, 3, 5, 3, 4, 2, 2, 6, 3, 3, 4, 3, 3, 3, 3, 3, 3, 3, 5, 3, 4, 4, 4, 5 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 LINKS Amiram Eldar, Table of n, a(n) for n = 1..10000 EXAMPLE The number of distinct prime divisors of 135 is 2 - the first term in the sequence. The number of distinct prime divisors of 357 is 3 - the second term in the sequence. The number of distinct prime divisors of 579 is 2 - the third term in the sequence. MAPLE read("transforms") : A104377 := proc(n) digcat2(digcat2(2*n+1, 2*n+3), 2*n+5) ; nops(numtheory[factorset](%)) ; end proc: # R. J. Mathar, Feb 03 2011 MATHEMATICA a[n_] := PrimeNu@ FromDigits@(Join @@ IntegerDigits /@ (2*n + {-1, 1, 3})); Array[a, 100] (* Amiram Eldar, Jan 27 2020 *) CROSSREFS Cf. A001221, A104186. Sequence in context: A079643 A329317 A118480 * A109337 A303539 A303540 Adjacent sequences: A104374 A104375 A104376 * A104378 A104379 A104380 KEYWORD nonn,base AUTHOR Parthasarathy Nambi, Apr 16 2005 EXTENSIONS Offset corrected and more terms added by Amiram Eldar, Jan 27 2020 STATUS approved

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Last modified December 7 18:28 EST 2023. Contains 367660 sequences. (Running on oeis4.)