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A337539
Number of primitive non-deficient numbers (A006039) dividing A337479(n).
4
2, 2, 2, 4, 2, 2, 2, 2, 2, 1, 2, 2, 2, 2, 1, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 4, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 3, 1, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 4, 2, 2, 2, 2, 2, 2, 2, 2, 1, 2, 2, 1, 2, 2, 2, 2, 2, 2, 2, 2, 4, 2, 3, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 5, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 1, 6, 2
OFFSET
1,1
COMMENTS
The numbers in A337479 are those that become a primitive nondeficient number (term of A006039) when each of their prime factors is replaced by the next larger prime number.
LINKS
FORMULA
a(n) = A337690(A337479(n)).
EXAMPLE
Table of n, A337479(n), a(n) and the relevant divisors starts:
n A337479(n) a(n) divisors in A006039
1 120 2 6, 20;
2 180 2 6, 20;
3 300 2 6, 20;
4 420 4 6, 20, 28, 70;
5 504 2 6, 28;
6 630 2 6, 70;
7 660 2 6, 20;
8 780 2 6, 20;
9 924 2 6, 28;
10 990 1 6;
11 1020 2 6, 20;
12 1050 2 6, 70;
PROG
(PARI)
isA071395(n) = if(sigma(n) <= 2*n, 0, fordiv(n, d, if((d != n)&&(sigma(d) >= 2*d), return(0))); (1)); \\ After code in A071395
isA006039(n) = ((sigma(n)==(2*n))||isA071395(n));
A337690(n) = sumdiv(n, d, isA006039(d));
A003961(n) = { my(f = factor(n)); for (i=1, #f~, f[i, 1] = nextprime(f[i, 1]+1)); factorback(f); };
isA337386(n) = { my(x=A003961(n)); (sigma(x)>=2*x); };
isA337479(n) = (isA337386(n)&&(1==sumdiv(n, d, isA337386(d))));
k=0; for(n=1, 2^15, if(isA337479(n), k++; print1(A337690(n), ", ")));
CROSSREFS
A006039, A337479 are used to define this sequence.
See A000203 and A023196 for definitions of deficient and nondeficient.
Subsequence of A337690.
Cf. A337386.
Sequence in context: A226534 A138260 A027389 * A374324 A111735 A211454
KEYWORD
nonn
AUTHOR
Antti Karttunen and Peter Munn, Sep 20 2020
STATUS
approved