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A236769 Numbers n such that lpf(2^n -1) < lpf(2^lpf(n) -1). 3
55, 77, 161, 169, 221, 275, 299, 323, 377, 385, 391, 437, 481, 493, 539, 551, 559, 605, 611, 629, 689, 697, 703, 715, 731, 779, 793, 799, 817, 847, 893, 901, 923, 935, 949, 1001, 1007, 1027, 1045, 1073, 1079, 1121, 1127, 1147, 1159, 1241, 1265, 1271, 1273, 1309 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

The numbers n for which A049479(n) < A049479(lpf(n)), where lpf(n) = A020639(n). All other n satisfy the equality (in particular all primes).

All terms are odd and composite. - Chai Wah Wu, Oct 04 2019

LINKS

Chai Wah Wu, Table of n, a(n) for n = 1..111

PROG

(PARI) lpf(n) = vecmin(factor(n)[, 1]);

lista() = {my(vlpfmp = readvec("A049479.log")); for (i=2, #vlpfmp, if (vlpfmp[i] < vlpfmp[lpf(i)], print1(i, ", ")); ); } \\ Michel Marcus, Jan 31 2014

CROSSREFS

Cf. A049479 (a question in the third comment).

Sequence in context: A050781 A060260 A152080 * A119224 A135984 A140377

Adjacent sequences:  A236766 A236767 A236768 * A236770 A236771 A236772

KEYWORD

nonn,more

AUTHOR

Thomas Ordowski, Jan 31 2014

EXTENSIONS

More terms from Michel Marcus, Jan 31 2014

More terms from Chai Wah Wu, Oct 04 2019

STATUS

approved

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Last modified December 10 12:25 EST 2019. Contains 329895 sequences. (Running on oeis4.)