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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 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

If a child is born to an n-year-old 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

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Last modified February 17 15:32 EST 2020. Contains 331998 sequences. (Running on oeis4.)