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A123387 Number of triangular numbers <= n-th prime. 3
2, 3, 3, 4, 5, 5, 6, 6, 7, 8, 8, 9, 9, 9, 10, 10, 11, 11, 12, 12, 12, 13, 13, 13, 14, 14, 14, 15, 15, 15, 16, 16, 17, 17, 17, 17, 18, 18, 18, 19, 19, 19, 20, 20, 20, 20, 21, 21, 21, 21, 22, 22, 22, 22, 23, 23, 23, 23, 24, 24, 24, 24, 25, 25, 25, 25, 26, 26, 26, 26, 27, 27, 27, 27 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Variant of A057062. - R. J. Mathar, Dec 13 2008

LINKS

G. C. Greubel, Table of n, a(n) for n = 1..5000

FORMULA

a(n) = A003056(A000040(n)) + 1 = A002024(A000040(n) + 1).

MATHEMATICA

f[n_] := Round[Sqrt[2n + 2]]; Table[f[Prime[n]], {n, 90}] (* Ray Chandler, Nov 13 2006 *)

CROSSREFS

Cf. A000040, A000217, A002024, A003056.

Sequence in context: A196393 A274089 A086335 * A123070 A057361 A136409

Adjacent sequences:  A123384 A123385 A123386 * A123388 A123389 A123390

KEYWORD

easy,nonn

AUTHOR

Giovanni Teofilatto, Nov 10 2006

EXTENSIONS

Extended by Ray Chandler, Nov 13 2006

STATUS

approved

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Last modified August 20 01:14 EDT 2019. Contains 326136 sequences. (Running on oeis4.)