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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 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Donovan Johnson, Table of n, a(n) for n = 1..1000

PROG

(PARI) isok(n) = eulerphi(3*n+1) == sigma(n); \\ Michel Marcus, Nov 21 2013

CROSSREFS

Cf. A000010, A000203, A067232.

Sequence in context: A279842 A043081 A091675 * A007648 A273481 A050586

Adjacent sequences:  A067230 A067231 A067232 * A067234 A067235 A067236

KEYWORD

nonn

AUTHOR

Benoit Cloitre, Feb 20 2002

STATUS

approved

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Last modified November 29 18:17 EST 2021. Contains 349416 sequences. (Running on oeis4.)