A143704 (1, 2, 3, 2^2, 5, 2*3, 7, 2^3, 3^2, 2*5, 11, 2^2*3, 13, 2*7, 3*5, ...) becomes ((1+2)*3, (2+2)*5, (2+3)*7, (2+3)*3, (2+2)*5, (11+2)*2, (3+13)*2, (7+3)*5, ...).

9, 20, 35, 15, 20, 26, 32, 50, 102, 10, 42, 56, 299, 15, 14, 48, 28, 93, 72, 88, 95, 18, 185, 63, 45, 92, 430, 44, 25, 1175, 18, 18, 21, 38, 132, 30, 39, 190, 1829, 12, 132, 68, 54, 36, 938, 68, 52, 852, 15, 150, 200, 8, 286, 65, 324, 32, 3569, 12, 204, 135, 93, 200, 25, 40

Offset

1,1

Links

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

Example

a(8)  = ( 7 +  3) *  5 = 10*5 = 50;
a(9)  = ( 2 +  4) * 17 = 102;
a(10) = ( 2 +  3) *  2 =  10;
a(11) = (19 +  2) *  2 =  42;
a(12) = ( 5 +  3) *  7 =  56;
a(13) = ( 2 + 11) * 23 = 199;
etc.

Maple

g:= proc(n) local L; L:= sort(ifactors(n)[2], (s, t) -> s[1]<t[1]);
  L:= map(proc(t) if t[2]=1 then t[1] else op(t) fi end proc, L);
  op(L);
end proc:
g(1):= 1:
B:= map(g, [$1..100]):
seq((B[3*i+1]+B[3*i+2])*B[3*i+3], i=0..(nops(B)-3)/3); # Robert Israel, Nov 16 2019

Crossrefs

Cf. A141287, A141261, A136735.

Sequence in context: A028566 A147479 A146680 * A128153 A249044 A109805

Adjacent sequences: A143701 A143702 A143703 * A143705 A143706 A143707

Keyword

nonn

Author

Juri-Stepan Gerasimov, Nov 13 2008

Extensions

Corrected (199 replaced by 299, 60 replaced by 30, 549 replaced by 54 etc.) by R. J. Mathar, Apr 18 2010

Status

approved