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Search: id:A125148
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| A125148 |
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a(n) = smallest prime p = z + x, where x is the n-th odd composite number not divisible by 5 and z is a multiple of 10. |
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+0
1
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| 19, 31, 37, 43, 59, 59, 61, 67, 73, 79, 97, 101, 97, 101, 103, 109, 131, 127, 139, 131, 163, 139, 163, 151, 163, 157, 163, 179, 181, 179, 181, 197, 193, 197, 199, 211, 223, 227, 229, 223, 227, 229, 241, 241, 257, 263, 257, 269, 263, 269, 271, 277, 283, 349
(list; graph; listen)
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OFFSET
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1,1
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COMMENT
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Conjecture: for every odd (prime or nonprime) number x>=1 that is not a multiple of 5 there exists a prime p such that p = z + x; where z is a multiple of 10.
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EXAMPLE
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The first and second odd composite number not divisible by 5 are 9 and 21, thus 19 = 10 + 9 and 31 = 10 + 21 are the first and second term of the sequence.
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PROGRAM
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(PARI) {m=280; for(x=2, m, if(x%2!=0&&x%5!=0&&!isprime(x), z=10; while(z<10^5&&!isprime(a=z+x), z+=10); print1(if(z<10^5, a, 0), ", ")))} - Klaus Brockhaus, Jan 24 2007
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CROSSREFS
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Sequence in context: A038542 A166659 A038672 this_sequence A040066 A159043 A040088
Adjacent sequences: A125145 A125146 A125147 this_sequence A125149 A125150 A125151
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KEYWORD
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nonn
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AUTHOR
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Tomas Xordan (xordan.tom(AT)gmail.com), Jan 11 2007
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EXTENSIONS
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Edited by Klaus Brockhaus (klaus-brockhaus(AT)t-online.de), Jan 24 2007
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