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A073896 a(1) = 1, a(n) = a(n-1) + k where k is smallest prime or composite number not used earlier according as a(n-1) is nonprime or prime. 0
1, 3, 7, 13, 21, 24, 29, 38, 45, 56, 69, 86, 105, 128, 157, 167, 179, 193, 208, 239, 255, 292, 333, 376, 423, 476, 535, 596, 663, 734, 807, 886, 969, 1058, 1155, 1256, 1359, 1466, 1575, 1688, 1815, 1946, 2083, 2101, 2240, 2389, 2409, 2560, 2717, 2880, 3047 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

Table of n, a(n) for n=1..51.

EXAMPLE

a(2) = 1+2 = 3 which is prime hence a(3) = 3+4 = 7 which is also a prime,a(4)= 7+6 = 13 which is also prime hence a(5) = 13 + 8 = 21, composite hence a(6) =21+ 3= 24.

CROSSREFS

Cf. A073895.

Sequence in context: A069194 A100531 A032409 * A299478 A299476 A077853

Adjacent sequences:  A073893 A073894 A073895 * A073897 A073898 A073899

KEYWORD

nonn

AUTHOR

Amarnath Murthy, Aug 18 2002

EXTENSIONS

More terms from Sam Alexander, Mar 01 2005

STATUS

approved

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Last modified April 5 16:53 EDT 2020. Contains 333245 sequences. (Running on oeis4.)