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A336964 Irregular triangle in which first row is 1, n-th row (n > 1) lists distinct prime numbers in the prime tower factorization of n. 2
1, 2, 3, 2, 5, 2, 3, 7, 2, 3, 2, 3, 2, 5, 11, 2, 3, 13, 2, 7, 3, 5, 2, 17, 2, 3, 19, 2, 5, 3, 7, 2, 11, 23, 2, 3, 2, 5, 2, 13, 3, 2, 7, 29, 2, 3, 5, 31, 2, 5, 3, 11, 2, 17, 5, 7, 2, 3, 37, 2, 19, 3, 13, 2, 3, 5, 41, 2, 3, 7, 43, 2, 11, 2, 3, 5, 2, 23, 47, 2, 3 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

The prime tower factorization of a number is defined in A182318.

The n-th row includes the n-th row of A027748.

LINKS

Rémy Sigrist, Table of n, a(n) for n = 1..10001 (rows for n = 1..4045)

EXAMPLE

Triangle begins:

     1    [1]

     2    [2]

     3    [3]

     4    [2]

     5    [5]

     6    [2, 3]

     7    [7]

     8    [2, 3]

     9    [2, 3]

    10    [2, 5]

    11    [11]

    12    [2, 3]

    13    [13]

    14    [2, 7]

    15    [3, 5]

PROG

(PARI) row(n) = { my (f=factor(n), p=f[, 1]~); for (k=1, #f~, if (f[k, 2]>1, p=concat(p, row(f[k, 2]))); ); if (#p==0, [1], Set(p)) }

CROSSREFS

Cf. A027748, A115588 (row lengths), A182318, A336965.

Sequence in context: A129088 A086418 A100761 * A027748 A328852 A000705

Adjacent sequences:  A336961 A336962 A336963 * A336965 A336966 A336967

KEYWORD

nonn,tabf

AUTHOR

Rémy Sigrist, Aug 09 2020

STATUS

approved

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Last modified December 7 13:08 EST 2021. Contains 349581 sequences. (Running on oeis4.)