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A086046 Sum of first n 4-almost primes. +0
6
16, 40, 76, 116, 170, 226, 286, 367, 451, 539, 629, 729, 833, 959, 1091, 1226, 1362, 1502, 1652, 1804, 1960, 2144, 2333, 2529, 2727, 2931, 3141, 3361, 3586, 3814, 4046, 4280, 4528, 4778, 5038, 5314, 5608, 5904, 6201, 6507, 6815, 7130, 7458, 7788, 8128 (list; graph; listen)
OFFSET

1,1

COMMENT

Elements in this sequence can themselves be 4-almost primes. a(1) = 16 = 2^4. a(2) = 40 = 2^3 * 5. a(19) = 1652 = 2^2 * 7 * 59. a(20) = 1804 = 2^2 * 11 * 41. a(31) = 4046 = 2 * 7 * 17^2. a(37) = 5608 = 2^3 * 701. a(39) = 6201 = 3^2 * 13 * 53. a(40) = 6507 = 3^3 * 241. a(42) = 7130 = 2 * 5 * 23 * 31. a(43) = 7458 = 2 * 3 * 11 * 113. Does this happen infinitely often? - Jonathan Vos Post (jvospost2(AT)yahoo.com), Dec 11 2004

EXAMPLE

a(2)=40 because sum of first two 4-almost primes i.e. 16+24 is 40.

CROSSREFS

Sequence in context: A121375 A070584 A132161 this_sequence A100958 A044093 A044474

Adjacent sequences: A086043 A086044 A086045 this_sequence A086047 A086048 A086049

KEYWORD

easy,nonn

AUTHOR

Shyam Sunder Gupta (guptass(AT)rediffmail.com), Aug 24 2003

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Last modified August 19 23:53 EDT 2008. Contains 142930 sequences.


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