A286190 Smallest k such that sopf(k) >= sopf(k+1) >= ... >= sopf(k+n), where sopf = A008472.

3, 13, 13, 491, 1516, 12721, 12721, 109453, 1473257, 120797465, 624141002, 4044619541, 136797949237, 315400191511, 1285600699441

Offset

1,1

Comments

Here sopf(k) is the sum of the distinct primes dividing k (A008472).

a(16) > 10^13.

Links

Table of n, a(n) for n=1..15.

Example

sopf(13) = 13, sopf(14) = 9, sopf(15) = 8, sopf(16) = 2. This is the first run of 4 nonincreasing values, so a(3) = 13.

Mathematica

sopf[n_] := If[n == 1, 0, Total[First /@ FactorInteger@n]]; s = Array[ sopf, 120000]; Table[ SelectFirst[ Range[ Length@s - n], Sort[t = Take[s, {#, # + n}]] == Reverse[t] &], {n, 8}]

Crossrefs

Cf A008472, A189882.

Sequence in context: A168437 A076747 A198452 * A224693 A043055 A101235

Adjacent sequences: A286187 A286188 A286189 * A286191 A286192 A286193

Keyword

nonn,more

Author

Giovanni Resta, May 04 2017

Status

approved