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A136568 Irregular triangle read by rows: row n contains the distinct values (in numerical order) making up the nonzero exponents in the prime-factorization of n. (Row 1 = (0).). 2
0, 1, 1, 2, 1, 1, 1, 3, 2, 1, 1, 1, 2, 1, 1, 1, 4, 1, 1, 2, 1, 1, 2, 1, 1, 1, 1, 3, 2, 1, 3, 1, 2, 1, 1, 1, 5, 1, 1, 1, 2, 1, 1, 1, 1, 3, 1, 1, 1, 1, 2, 1, 2, 1, 1, 1, 4, 2, 1, 2, 1, 1, 2, 1, 1, 3, 1, 1, 3, 1, 1, 1, 1, 2, 1, 1, 1, 2, 6, 1, 1, 1, 1, 2, 1, 1 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,4

COMMENTS

Row n, for n>=2, contains A071625(n) terms.

LINKS

Harvey P. Dale, Table of n, a(n) for n = 1..1000

EXAMPLE

4200 = 2^3 * 3^1 * 5^2 * 7^1. The exponents of the prime factorization are therefore 3,1,2,1. Therefore row 4200 is (1,2,3).

MATHEMATICA

Join[{0}, Flatten[Rest[Table[Union[Transpose[FactorInteger[n]][[2]]], {n, 100}]]]] (* Harvey P. Dale, Mar 19 2013 *)

CROSSREFS

Cf. A071625, A136565.

Sequence in context: A278113 A242012 A086290 * A152157 A039961 A108299

Adjacent sequences:  A136565 A136566 A136567 * A136569 A136570 A136571

KEYWORD

nonn,tabf

AUTHOR

Leroy Quet, Jan 07 2008

EXTENSIONS

More terms from Harvey P. Dale, Mar 19 2013

STATUS

approved

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Last modified July 5 03:05 EDT 2020. Contains 335457 sequences. (Running on oeis4.)