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A067544 Numbers n such that phi(n*(n+1)*(n+2)/6)/phi(n*(n+1)/2) is not an integer where phi(n)=A000010(n) is the Euler totient function. 0
8, 9, 18, 27, 44, 45, 53, 62, 80, 81, 90, 98, 99, 108, 116, 126, 134, 135, 143, 162, 171, 189, 198, 224, 225, 233, 234, 251, 260, 261, 270, 279, 287, 288, 296, 315, 332, 350, 351, 387, 413, 422, 423, 441, 449, 450, 458, 459, 468, 476, 477, 503, 504, 512, 522 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Often a(k)==0 (mod 3) and if a(k+1)-a(k)=1 then a(k+1)==0 (mod 3)

LINKS

Table of n, a(n) for n=1..55.

CROSSREFS

Sequence in context: A159836 A230542 A069809 * A022313 A120311 A061414

Adjacent sequences:  A067541 A067542 A067543 * A067545 A067546 A067547

KEYWORD

nonn

AUTHOR

Benoit Cloitre, Jan 28 2002

STATUS

approved

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Last modified October 22 22:34 EDT 2019. Contains 328335 sequences. (Running on oeis4.)