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A063449
Numbers k for which d(k+1) > 2d(k), where d(j) = A000005(j).
1
11, 17, 19, 23, 29, 31, 35, 41, 43, 47, 53, 59, 67, 71, 79, 83, 89, 95, 97, 101, 103, 107, 109, 111, 113, 119, 125, 127, 131, 137, 139, 143, 149, 151, 155, 159, 161, 163, 167, 169, 173, 179, 181, 191, 197, 199, 203, 209, 211, 215, 219, 223, 227, 229, 233, 239
OFFSET
1,1
COMMENTS
d(p+1) >= 2d(p) holds for all primes p and for some integers, as well.
LINKS
EXAMPLE
n=29: 2d(29) = 2*2 = 4 < 8 = d(30);
n=95: 2d(95) = 2*4 = 8 < 12 = d(96).
MATHEMATICA
Position[Partition[DivisorSigma[0, Range[250]], 2, 1], _?(2#[[1]]<#[[2]]&), 1, Heads->False]//Flatten (* Harvey P. Dale, Nov 16 2020 *)
PROG
(PARI) { n=0; for (m=1, 10^9, if (numdiv(m + 1) > 2*numdiv(m), write("b063449.txt", n++, " ", m); if (n==1000, break)) ) } \\ Harry J. Smith, Aug 21 2009
CROSSREFS
Cf. A000005.
Sequence in context: A050891 A226630 A061751 * A157996 A050713 A217063
KEYWORD
nonn
AUTHOR
Labos Elemer, Jul 24 2001
EXTENSIONS
Edited by Jon E. Schoenfield, Sep 05 2017
STATUS
approved