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A067233
Numbers n such that phi(3n+1) = sigma(n).
2
3, 21, 23, 27, 30, 65, 69, 95, 133, 143, 203, 253, 264, 413, 447, 537, 618, 667, 672, 715, 863, 897, 1092, 1122, 1221, 1265, 1343, 1824, 2367, 2757, 2765, 3009, 3231, 3471, 3605, 3683, 3741, 4088, 4195, 4578, 5838, 6295, 6533, 6747, 7689, 7701, 9548
OFFSET
1,1
LINKS
PROG
(PARI) isok(n) = eulerphi(3*n+1) == sigma(n); \\ Michel Marcus, Nov 21 2013
CROSSREFS
KEYWORD
nonn
AUTHOR
Benoit Cloitre, Feb 20 2002
STATUS
approved