

A092405


a(n) = tau(n) + tau(n+1), where tau(n) = A000005(n), the number of divisors of n.


5



3, 4, 5, 5, 6, 6, 6, 7, 7, 6, 8, 8, 6, 8, 9, 7, 8, 8, 8, 10, 8, 6, 10, 11, 7, 8, 10, 8, 10, 10, 8, 10, 8, 8, 13, 11, 6, 8, 12, 10, 10, 10, 8, 12, 10, 6, 12, 13, 9, 10, 10, 8, 10, 12, 12, 12, 8, 6, 14, 14, 6, 10, 13, 11, 12, 10, 8, 10, 12, 10, 14, 14, 6, 10, 12, 10, 12, 10, 12, 15, 9, 6, 14, 16
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OFFSET

1,1


COMMENTS

If a child is born to an nyearold parent, this is the number of times the age of the parent will be a multiple of the age of the child. E.g., if n = 27, this will happen at the ages (28, 1), (29, 1),(30, 2), (30, 3), (32, 4), (35, 7), (42, 14), (36, 9), (54, 27), (56, 28).  Alexander Piperski, Sep 10 2018


LINKS

Antti Karttunen, Table of n, a(n) for n = 1..20000


MATHEMATICA

Total /@ Partition[Array[DivisorSigma[0, #] &, 85], 2, 1] (* Michael De Vlieger, Sep 18 2018 *)


PROG

(PARI) for(i=1, 60, print1(", "sigma(i, 0)+sigma(i+1, 0)))
(PARI) A092405(n) = (numdiv(n)+numdiv(1+n)); \\ Antti Karttunen, Oct 07 2017


CROSSREFS

Cf. A000005, A175143.
Sequence in context: A120677 A266898 A098200 * A130234 A108852 A179413
Adjacent sequences: A092402 A092403 A092404 * A092406 A092407 A092408


KEYWORD

nonn


AUTHOR

Jon Perry, Mar 22 2004


EXTENSIONS

Extended by Ray Chandler, Mar 05 2010


STATUS

approved



