A111290 a(1)=1, a(n) = n + (sum of distinct primes dividing a(n-1)).

1, 2, 5, 9, 8, 8, 9, 11, 20, 17, 28, 21, 23, 37, 52, 31, 48, 23, 42, 32, 23, 45, 31, 55, 41, 67, 94, 77, 47, 77, 49, 39, 49, 41, 76, 57, 59, 97, 136, 59, 100, 49, 50, 51, 65, 64, 49, 55, 65, 68, 70, 66, 69, 80, 62, 89, 146, 133, 85, 82, 104, 77, 81, 67, 132, 82, 110, 86, 114, 94

Offset

1,2

Links

Harvey P. Dale, Table of n, a(n) for n = 1..1000

Example

a(10) = 10 + (sum of distinct primes dividing 20) = 10 + 2 + 5 = 17.

Mathematica

nxt[{n_, a_}]:={n+1, n+1+Total[Transpose[FactorInteger[a]][[1]]]}; Join[{1}, Transpose[ NestList[nxt, {2, 2}, 70]][[2]]] (* Harvey P. Dale, Mar 11 2015 *)

Prog

(PARI) b=1; for(i=2, 100, v=factor(b); b=i+sum(j=1, matsize(v)[1], v[j, 1]); print1(b, ", ")) (Klasen)

Crossrefs

Sequence in context: A104956 A360897 A020820 * A129140 A002580 A196408

Adjacent sequences: A111287 A111288 A111289 * A111291 A111292 A111293

Keyword

nonn

Author

Leroy Quet, Nov 01 2005

Extensions

More terms from Lambert Klasen (lambert.klasen(AT)gmx.net), Nov 06 2005

Status

approved