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A055600
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Numbers of form 2^i*3^j+1 with i, j >= 0.
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12
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2, 3, 4, 5, 7, 9, 10, 13, 17, 19, 25, 28, 33, 37, 49, 55, 65, 73, 82, 97, 109, 129, 145, 163, 193, 217, 244, 257, 289, 325, 385, 433, 487, 513, 577, 649, 730, 769, 865, 973, 1025, 1153, 1297, 1459, 1537, 1729, 1945, 2049, 2188, 2305, 2593, 2917, 3073, 3457, 3889
(list; graph; refs; listen; history; internal format)
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OFFSET
| 0,1
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COMMENTS
| If X is an n-set and Y a fixed (n-5)-subset of X then a(n-5) is equal to the number of 2-subsets of X intersecting Y. - Milan R. Janjic (agnus(AT)blic.net), Aug 15 2007
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REFERENCES
| G. Everest, P. Rogers and T. Ward, A higher-rank Mersenne problem, pp. 95-107 of ANTS 2002, Lect. Notes Computer Sci. 2369 (2002).
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LINKS
| Milan Janjic, Two Enumerative Functions
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FORMULA
| a(n)=A003586(n)+1
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EXAMPLE
| a(7)=13 since 13=2^2*3^1+1
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CROSSREFS
| Primes in this sequence give A005109 (Class 1- or Pierpoint primes).
Sequence in context: A032955 A060526 A036408 * A139528 A178434 A117290
Adjacent sequences: A055597 A055598 A055599 * A055601 A055602 A055603
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KEYWORD
| easy,nonn
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AUTHOR
| Henry Bottomley (se16(AT)btinternet.com), Jun 01 2000
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