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A324342
If 2n = 2^e1 + ... + 2^ek [e1 .. ek distinct], then a(n) is the minimal number of primorials (A002110) that add to A002110(e1) * ... * A002110(ek).
12
1, 1, 1, 2, 1, 2, 6, 6, 1, 2, 6, 2, 10, 10, 8, 16, 1, 2, 6, 12, 6, 12, 24, 20, 18, 20, 28, 28, 26, 6, 18, 24, 1, 2, 6, 12, 14, 12, 20, 6, 18, 18, 22, 26, 38, 20, 16, 16, 24, 32, 42, 44, 34, 50, 68, 70, 36, 54, 60, 54, 70, 56, 60, 82, 1, 2, 6, 12, 12, 6, 18, 36, 12, 24, 28, 34, 34, 50, 50, 72, 22, 26, 28, 34, 38, 54, 40, 52, 28, 38, 56
OFFSET
0,4
COMMENTS
When A283477(n) is written in primorial base (A049345), then a(n) is the sum of digits (with unlimited digit values), thus also the minimal number of primorials (A002110) that add to A283477(n).
Number of prime factors in A324289(n), counted with multiplicity.
Each subsequence starting at each n = 2^k is converging towards A283477: 1, 2, 6, 12, 30, 60, 180, 360, 210, 420, etc. See also comments in A324289.
FORMULA
a(n) = A276150(A283477(n)).
a(n) >= A324341(n).
a(2^n) = 1 for all n >= 0.
PROG
(PARI)
A002110(n) = prod(i=1, n, prime(i));
A030308(n, k) = bittest(n, k);
A283477(n) = prod(i=0, #binary(n), if(0==A030308(n, i), 1, A030308(n, i)*A002110(1+i)));
A276150(n) = { my(s=0, m); forprime(p=2, , if(!n, return(s)); m = n%p; s += m; n = (n-m)/p); };
KEYWORD
nonn
AUTHOR
Antti Karttunen, Feb 23 2019
STATUS
approved