A037280 If n is composite replace n with the concatenation of its nontrivial divisors [ A037279 ] then divide out any factors of 2.

1, 1, 3, 1, 5, 23, 7, 3, 3, 25, 11, 1173, 13, 27, 35, 31, 17, 2369, 19, 12255, 37, 211, 23, 586703, 5, 213, 39, 12357, 29, 23561015, 31, 1551, 311, 217, 57, 117345609, 37, 219, 313, 6145255, 41, 23671421, 43, 120561, 35915, 223, 47, 2933515203, 7, 251025, 317

Offset

1,3

Links

Table of n, a(n) for n=1..51.

Example

Divisors of 12 are 1,2,3,4,6,12, so 12 -> 2346 = 2*1173 -> 1173 = a(12).

Maple

with(numtheory):ds:=proc(s) local j: RETURN(add(s[j]*10^(j-1), j=1..nops(s))):end: a:=proc(n) options remember: local d, i, l, m: if n<3 then RETURN(1) else if not isprime(n) then d:=divisors(n): l:=nops(d): m:=ds([seq(op(convert(d[l-i+1], base, 10)), i=2..l-1)]): RETURN(m/piecewise(m mod 2=1, 1, 2^(ifactors(m)[2][1][2]))) else RETURN(n) fi fi: end; seq(a(n), n=1..70); # C. Ronaldo

Crossrefs

Cf. A037279.

Sequence in context: A039512 A140825 A265981 * A352009 A324204 A168611

Adjacent sequences: A037277 A037278 A037279 * A037281 A037282 A037283

Keyword

nonn,easy,base

Author

N. J. A. Sloane

Extensions

More terms from Erich Friedman

Status

approved