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A319355
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Filter sequence constructed from the lengths of arithmetic progressions occurring among the divisors of n.
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2
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1, 2, 2, 3, 2, 4, 2, 5, 3, 5, 2, 6, 2, 5, 4, 7, 2, 8, 2, 9, 5, 5, 2, 10, 3, 5, 5, 11, 2, 12, 2, 9, 5, 5, 5, 13, 2, 5, 5, 14, 2, 15, 2, 9, 16, 5, 2, 17, 3, 9, 5, 9, 2, 18, 5, 15, 5, 5, 2, 19, 2, 5, 9, 20, 5, 18, 2, 9, 5, 21, 2, 22, 2, 5, 8, 9, 5, 15, 2, 23, 7, 5, 2, 24, 5, 5, 5, 21, 2, 25, 4, 9, 5, 5, 5, 26, 2, 9, 9, 27, 2, 15, 2, 21, 28
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OFFSET
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1,2
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COMMENTS
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Restricted growth sequence transform of A319354.
For all i, j:
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LINKS
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PROG
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(PARI)
up_to = 65537;
rgs_transform(invec) = { my(om = Map(), outvec = vector(length(invec)), u=1); for(i=1, length(invec), if(mapisdefined(om, invec[i]), my(pp = mapget(om, invec[i])); outvec[i] = outvec[pp] , mapput(om, invec[i], i); outvec[i] = u; u++ )); outvec; };
A319354(n) = if(1==n, 2, my(d=divisors(n), m=1); for(i=1, (#d-1), for(j=(i+1), #d, my(c=1, k=d[j], s=(d[j]-d[i])); while(!(n%k), k+=s; c++); m *= prime(c))); (m));
v319355 = rgs_transform(vector(up_to, n, A319354(n)));
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CROSSREFS
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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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