This site is supported by donations to The OEIS Foundation. Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A105965 Numbers n such that n = 2^i_1+2^i_2+...2^i_k = b(j_1)*b(j_2)*...b(j_k) for distinct i's and distinct j's, where b is A050376. 0

%I

%S 2,4,6,10,12,16,18,20,33,34,36,42,48,56,65,68,70,80,84,88,104,120,129,

%T 138,140,144,152,200,210,216,224,256,266,270,272,273,276,290,296,312,

%U 322,328,330,336,352,360,385,390,392,408,416,420,448,456,480,514,518

%N Numbers n such that n = 2^i_1+2^i_2+...2^i_k = b(j_1)*b(j_2)*...b(j_k) for distinct i's and distinct j's, where b is A050376.

%C May be called ambipartite additive-multiplicative numbers.

%C If the exponents in the prime factorization of n are a_1, a_2, ..., a_k, then n is in this sequence iff A000120(n) = sum_{i = 1..k} A000120(a_i).

%C Numbers n such that A000120(n)=A064547(n).

%C Numbers n such that n=2^i_1+2^i_2+...2^i_k=b(j_1)*b(j_2)*...b(j_k) for distinct i's and distinct j's, where b is A050376. For all i's = j's, n = A052330(n)= 4, 36, ...? - _Thomas Ordowski_, May 11 2005

%e 16=2^4=2^(2^2), 33=1+32=3*11, 42=2+8+32=2*3*7, 120=8+16+32+64=2*3*4*5.

%e 2 = 2^1 = 2^(2^0)

%e 4 = 2^2 = 2^(2^1)

%e 6 = 2 + 4 = 2 * 3

%e 10 = 2 + 8 = 2 * 5

%e 12 = 4 + 8 = 3 * 4

%e 16 = 2^4 = 2^(2^2)

%e 18 = 2 + 16 = 2 * 9

%e 20 = 4 + 16 = 4 * 5

%e 33 = 1 + 32 = 3 * 11

%e 34 = 2 + 32 = 2 * 17

%e 36 = 4 + 32 = 4 * 9

%e 42 = 2 + 8 + 32 = 2 * 3 * 7

%e 48 = 16 + 32 = 3 * 16

%e 56 = 8 + 16 + 32 = 2 * 4 * 7

%e 65 = 1 + 64 = 5 * 13

%e 68 = 4 + 64 = 4 * 17

%e 70 = 2 + 4 + 64 = 2 * 5 * 7

%e 80 = 16 + 64 = 5 * 16

%e 84 = 4 + 16 + 64 = 3 * 4 * 7

%e 88 = 8 + 16 + 64 = 2 * 4 * 11

%e 104 = 8 + 32 + 64 = 2 * 4 * 13

%e 120 = 8 + 16 + 32 + 64 = 2 * 3 * 4 * 5

%o (PARI) f(n) =if (n, n%2 + f(n\2), 0); g(n) = local(a); a = factor(n); f(n) == sum(i = 1, matsize(a), f(a[i, 2])); for (n = 1, 1000, if (g(n), print1(n" "))); (Wasserman)

%Y Cf. A000120.

%Y Cf. A052330, A000120 and A064547.

%K nonn

%O 1,1

%A _Thomas Ordowski_, Apr 28 2005

%E More terms from _David Wasserman_, Apr 29 2005

%E Examples from _Thomas Ordowski_, May 11 2005

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

Last modified October 23 17:32 EDT 2019. Contains 328373 sequences. (Running on oeis4.)