A374075 Starting with a(1) = 1, a(n) = a(n-1) + the sum of the distinct primes that divide n but not a(n-1).

1, 3, 3, 5, 5, 10, 17, 19, 22, 27, 38, 41, 54, 61, 69, 71, 88, 91, 110, 110, 120, 131, 154, 157, 162, 175, 178, 185, 214, 222, 253, 255, 266, 283, 295, 300, 337, 358, 374, 379, 420, 420, 463, 476, 484, 507, 554, 557, 564, 569, 589, 604, 657, 659, 675, 684, 684, 713, 772, 780, 841, 874, 884, 884

Offset

1,2

Links

Robert Israel, Table of n, a(n) for n = 1..10000

Example

a(9) = 22; the primes dividing 10 are 2 and 5, but 2 also divides 22, so a(10) = 22 + 5 = 27.

Maple

R:=1: v:= 1:
for n from 2 to 100 do
  v:= v + convert(select(p -> v mod p <> 0, numtheory:-factorset(n)), `+`);
  R:= R, v
od:
R;

Mathematica

n = 1; NestList[Function[k, n++; k + Total@ Select[FactorInteger[n][[All, 1]], CoprimeQ[#, k] &]], 1, 63] (* Michael De Vlieger, Jun 28 2024 *)

Crossrefs

Cf. A114707.

Sequence in context: A283843 A241508 A099536 * A345001 A082434 A078752

Adjacent sequences: A374072 A374073 A374074 * A374076 A374077 A374078

Keyword

nonn

Author

Robert Israel, Jun 27 2024

Status

approved