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A348747
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Fully multiplicative with a(2) = 1, a(3) = 2, a(5) = 3, a(A002144(1+n)) = A002144(n) and a(A002145(1+n)) = a(A002145(1+n)) for all n >= 1, where A002144 and A002145 give the primes of the form 4k+1 and 4k+3 respectively.
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5
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1, 1, 2, 1, 3, 2, 7, 1, 4, 3, 11, 2, 5, 7, 6, 1, 13, 4, 19, 3, 14, 11, 23, 2, 9, 5, 8, 7, 17, 6, 31, 1, 22, 13, 21, 4, 29, 19, 10, 3, 37, 14, 43, 11, 12, 23, 47, 2, 49, 9, 26, 5, 41, 8, 33, 7, 38, 17, 59, 6, 53, 31, 28, 1, 15, 22, 67, 13, 46, 21, 71, 4, 61, 29, 18, 19, 77, 10, 79, 3, 16, 37, 83, 14, 39, 43, 34, 11, 73
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OFFSET
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1,3
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LINKS
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FORMULA
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PROG
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(PARI) A348747(n) = { my(f=factor(n)); for(k=1, #f~, if(f[k, 1]<=3, f[k, 1]--, if(5==f[k, 1], f[k, 1]=3, if(1==(f[k, 1]%4), forstep(i=primepi(f[k, 1])-1, 0, -1, if(1==(prime(i)%4), f[k, 1]=prime(i); break)))))); factorback(f); };
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CROSSREFS
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KEYWORD
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nonn,mult
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AUTHOR
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STATUS
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approved
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