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A005145 n copies of n-th prime. 7
2, 3, 3, 5, 5, 5, 7, 7, 7, 7, 11, 11, 11, 11, 11, 13, 13, 13, 13, 13, 13, 17, 17, 17, 17, 17, 17, 17, 19, 19, 19, 19, 19, 19, 19, 19, 23, 23, 23, 23, 23, 23, 23, 23, 23, 29, 29, 29, 29, 29, 29, 29, 29, 29, 29, 31, 31, 31, 31, 31, 31, 31, 31, 31, 31, 31 (list; table; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

a = A000040(A002024). - Joseph Biberstine (jrbibers(AT)indiana.edu), Aug 14 2006

Seen as a triangle read by rows: T(n,k) = A000040(n), 1<=k<=n; row sums = A033286; central terms = A031368. - Reinhard Zumkeller, Aug 05 2009

REFERENCES

Douglas Hofstadter, "Fluid Concepts and Creative Analogies: Computer Models of the Fundamental Mechanisms of Thought".

LINKS

Reinhard Zumkeller, Rows n = 1..125 of triangle, flattened

FORMULA

a(n) = prime(floor(1/2 + sqrt(2*n))). - Joseph Biberstine (jrbibers(AT)indiana.edu), Aug 14 2006

MATHEMATICA

Table[Prime[Floor[1/2 + Sqrt[2*n]]], {n, 1, 80}] - Joseph Biberstine (jrbibers(AT)indiana.edu), Aug 14 2006

Flatten[Table[Table[Prime[n], {n}], {n, 12}]] (* Alonso del Arte, Jan 18 2012 *)

PROG

(Haskell)

a005145 n k = a005145_tabl !! (n-1) !! (k-1)

a005145_row n = a005145_tabl !! (n-1)

a005145_tabl = zipWith ($) (map replicate [1..]) a000040_list

a005145_list = concat a005145_tabl

-- Reinhard Zumkeller, Jul 12 2014, Mar 18 2011, Oct 17 2010

(PARI) a(n) = prime(round(sqrt(2*n))) \\ Charles R Greathouse IV, Oct 23 2015

CROSSREFS

Cf. A002024, A175944.

Sequence in context: A053046 A261179 A066658 * A280740 A156350 A076367

Adjacent sequences:  A005142 A005143 A005144 * A005146 A005147 A005148

KEYWORD

nonn,nice,tabl

AUTHOR

Russ Cox

STATUS

approved

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Last modified November 19 22:34 EST 2019. Contains 329323 sequences. (Running on oeis4.)