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A328620
Number of nonleading zeros in primorial base expansion of n, a(0) = 0 by convention.
7
0, 0, 1, 0, 1, 0, 2, 1, 1, 0, 1, 0, 2, 1, 1, 0, 1, 0, 2, 1, 1, 0, 1, 0, 2, 1, 1, 0, 1, 0, 3, 2, 2, 1, 2, 1, 2, 1, 1, 0, 1, 0, 2, 1, 1, 0, 1, 0, 2, 1, 1, 0, 1, 0, 2, 1, 1, 0, 1, 0, 3, 2, 2, 1, 2, 1, 2, 1, 1, 0, 1, 0, 2, 1, 1, 0, 1, 0, 2, 1, 1, 0, 1, 0, 2, 1, 1, 0, 1, 0, 3, 2, 2, 1, 2, 1, 2, 1, 1, 0, 1, 0, 2, 1, 1, 0
OFFSET
0,7
FORMULA
a(n) = A001221(A328612(n)).
a(n) = A079067(A276086(n)).
a(A002110(n)) = n for all n >= 0.
MATHEMATICA
a[n_] := Module[{k = n, p = 2, s = 0, r}, While[{k, r} = QuotientRemainder[k, p]; k != 0 || r != 0, If[r == 0, s++]; p = NextPrime[p]]; s]; Array[a, 100, 0] (* Amiram Eldar, Mar 13 2024 *)
PROG
(PARI) A328620(n) = { my(s=0, p=2); while(n, s += (0==(n%p)); n = n\p; p = nextprime(1+p)); (s); };
CROSSREFS
Cf. A257510 for an analogous sequence.
Sequence in context: A078659 A374080 A079690 * A257510 A305445 A225721
KEYWORD
nonn,base
AUTHOR
Antti Karttunen, Oct 23 2019
STATUS
approved