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A058973
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First integer reached in A058972.
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3
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1, 2, 3, 2, 4, 2, 5, 9, 2, 4, 8, 8, 9, 9, 10, 8, 8, 11, 2, 2, 12, 2, 13, 13, 14, 15, 4, 16, 2, 17, 4, 35, 19, 8, 23, 9, 8, 22, 25, 2, 26, 25, 2, 2, 24, 28, 8, 10, 4, 29, 2, 26, 29, 2, 2, 35, 33, 6, 2, 38, 33, 33, 40, 2, 68, 4, 8, 44, 41, 8, 4, 46, 35, 43, 49, 50, 2, 42, 8, 40, 58, 4, 59, 43, 61
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OFFSET
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1,2
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LINKS
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EXAMPLE
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A058972(1) = 3: f(3/1) = 3/3 = 1 = a(1);
A058972(2) = 9: f(9/1) = 8/4 = 2 = a(2);
A058972(3) = 15: f(15/1) = 15/5 = 3 = a(3);
A058972(4) = 24: f(24/1) = 6/3 = 2 = a(4).
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PROG
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(PARI) f2(p, q) = (sigma(p+q)-p-q)/numdiv(p+q);
f1(r) = f2(numerator(r), denominator(r));
loop(list) = {my(v=Vecrev(list)); for (i=2, #v, if (v[i] == v[1], return(1)); ); }
ff(n) = {my(ok=0, m=f2(n, 1), list=List()); while(denominator(m) != 1, m = f1(m); listput(list, m); if (loop(list), return (0)); ); return(m); }
lista(nn) = {for (n=1, nn, my(x=ff(n)); if (x, print1(x, ", ")); ); } \\ Michel Marcus, Feb 09 2022
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CROSSREFS
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KEYWORD
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nonn,easy
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AUTHOR
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EXTENSIONS
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Corrected and extended by Antonio G. Astudillo (afg_astudillo(AT)lycos.com), Mar 22 2003
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STATUS
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approved
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