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A138172 Even n where d(n) < d(n+1), where d(n) = number of positive divisors of n. 3
62, 74, 134, 146, 164, 188, 194, 206, 254, 274, 278, 284, 314, 356, 362, 386, 398, 404, 422, 428, 454, 458, 482, 494, 524, 538, 554, 566, 584, 614, 626, 662, 674, 692, 734, 746, 758, 764, 794, 818, 824, 854, 866, 890, 914, 926, 934, 944, 956, 974, 998, 1004, 1028 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Terms calculated by M. F. Hasler.

First term == 0 (mod 6) is a(133) = 2274. - Jianing Song, Apr 03 2018

LINKS

Jianing Song and Muniru A Asiru, Table of n, a(n) for n = 1..10000(Terms 1 through 1019 from Jianing Song)

MAPLE

with(numtheory): A138172:=n->`if`(n mod 2 = 0 and tau(n) < tau(n+1), n, NULL): seq(A138172(n), n=1..1000); # Wesley Ivan Hurt, Apr 10 2015

MATHEMATICA

2 Position[Partition[Array[DivisorSigma[0, #] &, 10^3, 2], 2, 2], _?(#1 < #2 & @@ # &)][[All, 1]] (* Michael De Vlieger, Apr 07 2018 *)

PROG

(PARI) lista(nn) = {forstep(n=2, nn, 2, if (numdiv(n) < numdiv(n+1), print1(n, ", ")); ); } \\ Michel Marcus, Apr 10 2015

(GAP) Filtered([2, 4..1300], n->Tau(n)<Tau(n+1)); # Muniru A Asiru, Apr 05 2018

CROSSREFS

Cf. A000005, A138046, A138171.

Sequence in context: A047823 A294738 A044997 * A074772 A074771 A342258

Adjacent sequences:  A138169 A138170 A138171 * A138173 A138174 A138175

KEYWORD

nonn

AUTHOR

Leroy Quet, Mar 03 2008

STATUS

approved

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Last modified July 29 22:13 EDT 2021. Contains 346346 sequences. (Running on oeis4.)