A280967 -id:A280967

Search: a280967 -id:a280967

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A280972

Numbers that appear in both A278909 and A280967 but not in A280971.

+20
2

765, 1275, 1467, 1503, 1515, 1695, 2910, 2975, 3066, 3423, 4335, 4539, 4605, 4862, 4923, 4947, 4975, 5110, 5295, 5335, 5375, 5559, 5787, 5790, 5835, 5885, 6069, 6123, 6495, 6735, 6783, 7035, 7134, 9195, 9567, 9583, 9645, 9819, 9915, 10087, 10155, 10218, 10234, 10491, 10686, 10959, 10983, 11211

(list; graph; refs; listen; history; text; internal format)

OFFSET

1,1

COMMENTS

Binary equivalent of the sequence representing Numbers that appear in both A176670 and A020342 but not A280928 (currently no members are known).

LINKS

Ely Golden, Table of n, a(n) for n = 1..896

EXAMPLE

765 = A278909(41) = A280967(32) but is not present in A280971.

CROSSREFS

Cf. A278909, A280967, A280971.

KEYWORD

nonn,base

AUTHOR

Ely Golden, Jan 11 2017

STATUS

approved

A280971

Composite numbers having the same bits as their prime factors (with multiplicity), including zero bits.

+10
2

159, 287, 303, 319, 591, 623, 679, 687, 699, 763, 1135, 1167, 1203, 1243, 1247, 1271, 1351, 1371, 1391, 1631, 2167, 2173, 2231, 2285, 2319, 2359, 2463, 2471, 2495, 2519, 2743, 2779, 2787, 2809, 2863, 2931, 2933, 2991, 3029, 3039, 3503, 4223, 4279, 4287, 4319, 4343, 4411, 4439, 4479, 4487

(list; graph; refs; listen; history; text; internal format)

OFFSET

1,1

COMMENTS

Binary equivalent of A280928.

Subsequence of A278909 as well as A280967. The terms in A278909 and A280967 but not this sequence are given by A280972.

LINKS

Ely Golden, Table of n, a(n) for n = 1..10000

PROG

(SageMath)

def factorbits(x):

if(x<2):

return (0, 0);

s=0; t=0

f=list(factor(x));

#ensures inequality of numfactorbits(x) and bin(x).count("1") if x is prime

if((len(f)==1)&(f[0][1]==1)):

return (0, 0);

for c in range(len(f)):

s+=bin(f[c][0]).count("1")*f[c][1]

t+=(bin(f[c][0]).count("0")-1)*f[c][1]

return (s, t);

counter=2

index=1

while(index<=10000):

if(factorbits(counter)==(bin(counter).count("1"), bin(counter).count("0")-1)):

print(str(index)+" "+str(counter))

index+=1;

counter+=1;