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Search: id:A092933
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| A092933 |
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Let 1,a,b,c,... be the numbers coprime to n in ascending order; then n belongs to this sequence if n = a partial sum of these numbers. |
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3
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| 1, 3, 4, 6, 16, 20, 24, 27, 54, 64, 80, 96, 120, 216, 243, 252, 256, 272, 320, 384, 410, 465, 480, 486, 500, 637, 715, 732, 864, 936, 1008, 1024, 1080, 1088, 1280, 1435, 1536, 1586, 1632, 1920, 1944, 2000, 2052, 2065, 2187, 2200, 2268, 2280, 3000, 3164, 3456
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OFFSET
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1,2
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COMMENT
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Sequence is infinite; it includes all powers of 4. More generally, if n is in this sequence, let i be the number just added to make the sum equal to n. If i+1 is divisible by every prime divisor of n, then n*m^2 is in the sequence for any number m whose prime divisors all divide n. This gives us subsequences 3*9^i, 6*4^i*9^j, 20*4^i*25^j, 120*4^i*9^j*25^k, etc. - Franklin T. Adams-Watters (FrankTAW(AT)Netscape.net), Dec 18 2006
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EXAMPLE
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6 is a member as 6 = 1+5. 16 is also a member.
The numbers coprime to 16 are 1,3,5,7,9,11,13,15. The partial sums are 1,4,9,16,25,...
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CROSSREFS
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Cf. A117892, A117893.
Sequence in context: A129827 A122727 A089249 this_sequence A122849 A068573 A138577
Adjacent sequences: A092930 A092931 A092932 this_sequence A092934 A092935 A092936
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KEYWORD
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nonn
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AUTHOR
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Amarnath Murthy (amarnath_murthy(AT)yahoo.com), Mar 22 2004
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EXTENSIONS
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More terms from Franklin T. Adams-Watters (FrankTAW(AT)Netscape.net), Dec 18 2006
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