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A341813
a(n) is the least integer k such that n/(Sum_{j=1..n} 1/phi(k*j)) is an integer.
2
1, 1, 4, 7, 2, 11, 22, 101, 53, 2, 25, 149, 75, 321, 10, 653, 3110, 907, 5926, 16829, 2505, 3174, 13178, 4323, 5931, 18033, 20231, 41698, 155533, 1323199, 1477613, 1133209, 65051, 109522, 152567, 610799, 33521, 8141, 2386, 156863, 239559, 1006091, 113097, 6353, 11434
OFFSET
1,3
FORMULA
a(n) <= A341810(n).
PROG
(PARI) a(n) = my(k=1); while (denominator(n/sum(j=1, n, 1/eulerphi(k*j))) != 1, k++); k; \\ Michel Marcus, Feb 20 2021
CROSSREFS
Sequence in context: A103887 A167046 A283745 * A088446 A362253 A076414
KEYWORD
nonn
AUTHOR
Seiichi Manyama, Feb 20 2021
STATUS
approved