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A141556 Composites of form (c(p(n))+p(c(n))), where c(n)=n-th composite and p(n)=n-th prime. 0
21, 49, 70, 77, 88, 105, 117, 176, 185, 192, 205, 236, 247, 292, 301, 309, 323, 345, 365, 394, 405, 411, 427, 435, 455, 478, 490, 501, 513, 538, 554, 567, 585, 622, 636, 640, 655, 675, 713, 747, 759, 767, 785, 794, 833, 845, 854, 862, 891, 905, 921, 933, 978 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Table of n, a(n) for n=1..53.

EXAMPLE

If n=1, c(1)=4, p(1)=2, then c(2)+p(4)=6+7=13 (prime).

If n=2, c(2)=6, p(2)=3, then c(3)+p(6)=8+13=21=a(1).

If n=3, c(3)=8, p(3)=5, then c(5)+p(8)=10+19=29 (prime).

If n=4, c(4)=9, p(4)=7, then c(7)+p(9)=14+23=37 (prime).

If n=5, c(5)=10, p(5)=11, then c(11)+p(10)=20+29=49=a(2).

If n=6, c(6)=12, p(6)=13, then c(13)+p(12)=22+37=59 (prime).

If n=7, c(7)=14, p(7)=17, then c(17)+p(14)=27+43=70=a(3).

If n=8, c(8)=15, p(8)=19, then c(19)+p(15)=30+47=77=a(4).

If n=9, c(9)=16, p(9)=23, then c(23)+p(16)=35+53=88=a(5).

If n=10, c(10)=18, p(10)=29, then=c(29)+p(18)=44+61=105=a(6).

If n=11, c(11)=20, p(11)=31, then c(31)+p(20)=46+71=117=a(7).

If n=12, c(12)=21, p(12)=37, then c(37)+p(21)=54+73=127 (prime).

If n=13, c(13)=22, p(13)=41, then c(41)+p(22)=58+79=137 (prime).

If n=14, c(14)=24, p(14)=43, then c(43)+p(24)=62+89=151 (prime).

If n=15, c(15)=25, p(15)=47, then c(47)+p(25)=66+97=163 (prime).

If n=16, c(16)=26, p(16)=53, then c(53)+p(26)=75+101=176=a(8), etc.

CROSSREFS

Cf. A000040, A002808.

Sequence in context: A140681 A138179 A020178 * A147281 A130062 A153441

Adjacent sequences:  A141553 A141554 A141555 * A141557 A141558 A141559

KEYWORD

nonn

AUTHOR

Juri-Stepan Gerasimov Aug 14 2008

EXTENSIONS

Edited and corrected by Ray Chandler, Aug 19 2008

STATUS

approved

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Last modified July 28 10:17 EDT 2014. Contains 244989 sequences.