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A240171
Numbers k such that k has more divisors than k-1.
1
2, 4, 6, 8, 10, 12, 14, 16, 18, 20, 24, 26, 28, 30, 32, 36, 38, 40, 42, 44, 48, 50, 52, 54, 56, 60, 62, 63, 64, 66, 68, 70, 72, 74, 75, 78, 80, 84, 88, 90, 92, 96, 98, 100, 102, 104, 108, 110, 112, 114, 116, 120, 122, 124, 126, 128, 130, 132, 135, 138, 140
OFFSET
1,1
COMMENTS
Numbers k such that A051950(k) > 0. - Robert Israel, Aug 03 2014
LINKS
EXAMPLE
22 has the same number of divisors as 21 (4 divisors), so 22 is not a term.
63 has 6 divisors, and 62 has only 4, so 63 is a term.
MAPLE
N:= 1000: # to get all entries <= N
L:= map(numtheory:-tau, [$1..N]):
A:= select(t -> L[t] > L[t-1], [$2..N]); # Robert Israel, Aug 03 2014
MATHEMATICA
Flatten[Position[Partition[DivisorSigma[0, Range[200]], 2, 1], _?(#[[1]]< #[[2]]&), {1}, Heads->False]]+1 (* Harvey P. Dale, Feb 08 2015 *)
PROG
(PARI)
for(n=1, 10^3, if(numdiv(n)>numdiv(n-1), print1(n, ", "))) \\ Derek Orr, Aug 02 2014
CROSSREFS
Sequence in context: A064720 A376952 A029741 * A221284 A272670 A234521
KEYWORD
nonn,easy
AUTHOR
J. Lowell, Aug 02 2014
STATUS
approved