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A143813
Sum of two powerful numbers greater than 1.
1
8, 12, 13, 16, 17, 18, 20, 24, 25, 29, 31, 32, 33, 34, 35, 36, 40, 41, 43, 44, 45, 48, 50, 52, 53, 54, 57, 58, 59, 61, 63, 64, 65, 68, 72, 73, 74, 76, 80, 81, 85, 88, 89, 90, 91, 96, 97, 98, 99, 100, 104, 106, 108, 109, 112, 113, 116, 117, 121, 124, 125, 127
OFFSET
1,1
COMMENTS
A076871 is the primary sequence.
EXAMPLE
8 = 4 + 4, 12 = 4 + 8, 13 = 4 + 9.
PROG
(PARI) isP(n)={
n>3 && vecmin(factor(n)[, 2])>1
};
sumset(a, b)={
my(c=vector(#a*#b));
for(i=1, #a,
for(j=1, #b,
c[(i-1)*#b+j]=a[i]+b[j]
)
);
vecsort(c, , 8)
};
upto(lim)={
my(v=select(isP, vector(floor(lim), i, i)));
select(n->n<=lim, sumset(v, v))
};
CROSSREFS
Sequence in context: A335160 A295782 A331801 * A290135 A225533 A143845
KEYWORD
nonn
AUTHOR
STATUS
approved