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1, 1, 1, 1, 1, 1, 1, 5, 7, 1, 1, 1, 1, 1, 1, 5, 1, 7, 1, 1, 1, 1, 1, 7, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 13, 7, 1, 1, 1, 1, 1, 13, 1, 1, 1, 1, 1, 7, 13, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 13, 1, 19, 1, 1, 1, 1, 13, 1, 7, 1, 1, 13, 1, 1, 1, 1, 1, 7, 1, 1, 13, 1, 1, 1, 1, 1, 1, 19, 1, 1, 1, 1, 7, 1, 13, 1, 13, 1, 1, 1, 1, 13
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OFFSET
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1,8
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LINKS
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FORMULA
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EXAMPLE
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For n = 128 = 2^7, A108951(128) = A034386(2)^7 = 128. As 128 = 4 * 30 + 1*6 + 1* 2, A276086(128) = 36015 = 7^4 * 5^1 * 3^1, and there are two such primes that both p and p-2 divide n, and p-2 is also prime, namely, 7 and 5, thus a(128) = 7*5 = 35. This is also the first occurrence of composite number in this sequence.
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PROG
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(PARI)
A034386(n) = prod(i=1, primepi(n), prime(i));
A276086(n) = { my(m=1, p=2); while(n, m *= (p^(n%p)); n = n\p; p = nextprime(1+p)); (m); };
A322356(n) = { my(f = factor(n), m=1); for(i=1, #f~, if(isprime(f[i, 1]+2)&&!(n%(f[i, 1]+2)), m *= (f[i, 1]+2))); (m); };
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CROSSREFS
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Cf. A002110, A034386, A108951, A276086, A324886, A329040, A322356, A329343, , A329344, A329347, A329348.
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KEYWORD
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nonn
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AUTHOR
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STATUS
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approved
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