A067543 - OEIS

A067543

Numbers k such that phi(k*(k+1)*(k+2)*(k+3)/4!)/phi(k*(k+1)*(k+2)/3!) is not an integer where phi(n) = A000010(n) is the Euler totient function.

6, 8, 16, 24, 40, 46, 54, 56, 64, 78, 80, 104, 118, 126, 128, 136, 144, 160, 176, 198, 208, 224, 240, 248, 280, 304, 328, 344, 358, 360, 376, 414, 416, 440, 464, 486, 488, 496, 520, 526, 544, 560, 568, 584, 616, 630, 640, 656, 680, 688, 726, 736, 784

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OFFSET

1,1

LINKS

Table of n, a(n) for n=1..53.

PROG

(PARI) isok(k) = denominator(eulerphi(k*(k+1)*(k+2)*(k+3)/4!)/eulerphi(k*(k+1)*(k+2)/3!)) != 1; \\ Michel Marcus, Dec 19 2023

CROSSREFS

Cf. A000010 (phi).

Sequence in context: A315939 A315940 A048228 * A006583 A011989 A270821

Adjacent sequences: A067540 A067541 A067542 * A067544 A067545 A067546

KEYWORD

nonn

AUTHOR

Benoit Cloitre, Jan 28 2002

EXTENSIONS

Incorrect 203 removed by Sean A. Irvine, Dec 19 2023

STATUS

approved