

A105212


a(1) = 668; for n > 1, a(n) = a(n1) + 1 + sum of distinct prime factors of a(n1) that are < a(n1).


6



668, 838, 1260, 1278, 1355, 1632, 1655, 1992, 2081, 2082, 2435, 2928, 2995, 3600, 3611, 3792, 3877, 3878, 4165, 4195, 5040, 5058, 5345, 6420, 6538, 7015, 7105, 7147, 8176, 8259, 11016, 11039, 11149, 11150, 11381, 12000, 12011, 12012, 12049, 12050
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OFFSET

1,1


COMMENTS

In Math. Mag. 48 (1975) 301 one finds "C. W. Trigg, C. C. Oursler and R. Cormier and J. L. Selfridge have sent calculations on Problem 886 [Nov 1973] for which we had received only partial results [Jan 1975]. Cormier and Selfridge sent the following results: There appear to be five sequences beginning with integers less than 1000 which do not merge. These sequences were carried out to 10^8 or more." The five sequences are A003508, A105210A105213.


LINKS

T. D. Noe, Table of n, a(n) for n = 1..2000
Doug Engel, Problem 886, Math. Mag., 48 (1975), 5758.


EXAMPLE

a(2)=838 because a(1)=668, the distinct prime factors of a(1) are 2 and 167; finally, 1 + 668 + 2 + 167 = 838.


MAPLE

with(numtheory): p:=proc(n) local nn, ct, s: if isprime(n)=true then s:=0 else nn:=convert(factorset(n), list): ct:=nops(nn): s:=sum(nn[j], j=1..ct):fi: end: a[1]:=668: for n from 2 to 46 do a[n]:=1+a[n1]+p(a[n1]) od:seq(a[n], n=1..46); # Emeric Deutsch, Apr 14 2005


PROG

(Haskell)
a105212 n = a105212_list !! (n1)
a105212_list = 668 : map
(\x > x + 1 + sum (takeWhile (< x) $ a027748_row x)) a105212_list
 Reinhard Zumkeller, Jan 15 2015


CROSSREFS

Cf. A003508, A027748, A105210, A105211, A105213.
Sequence in context: A138563 A327908 A092797 * A067875 A224558 A250670
Adjacent sequences: A105209 A105210 A105211 * A105213 A105214 A105215


KEYWORD

nonn,easy


AUTHOR

R. K. Guy, Apr 14 2005


EXTENSIONS

More terms from Robert G. Wilson v and Emeric Deutsch, Apr 14 2005


STATUS

approved



