A381032 The radix prime of the least significant digit > 1 in the primorial base expansion of n, or 1 if there is no such digit.

1, 1, 1, 1, 3, 3, 1, 1, 1, 1, 3, 3, 5, 5, 5, 5, 3, 3, 5, 5, 5, 5, 3, 3, 5, 5, 5, 5, 3, 3, 1, 1, 1, 1, 3, 3, 1, 1, 1, 1, 3, 3, 5, 5, 5, 5, 3, 3, 5, 5, 5, 5, 3, 3, 5, 5, 5, 5, 3, 3, 7, 7, 7, 7, 3, 3, 7, 7, 7, 7, 3, 3, 5, 5, 5, 5, 3, 3, 5, 5, 5, 5, 3, 3, 5, 5, 5, 5, 3, 3, 7, 7, 7, 7, 3, 3, 7, 7, 7, 7, 3, 3, 5, 5, 5, 5, 3, 3, 5

Offset

0,5

Links

Antti Karttunen, Table of n, a(n) for n = 0..65537

Index entries for sequences related to primorial base.

Formula

a(n) = A008578(1+A328828(n)).

a(n) = A020639(A328572(n)) = A249739(A276086(n)).

For all n, a(n) divides A327860(n).

Prog

(PARI) A381032(n) = { my(p=2); while(n, if((n%p)>1, return(p)); n = n\p; p = nextprime(1+p)); (1); };

Crossrefs

Cf. A008578, A020639, A249739, A276086, A327860, A328572, A328828, A381033, A381034.

Cf. A088860 (positions of records for values > 1), A276156 (positions of 1's).

Cf. also A053669, A351566.

Sequence in context: A326057 A130778 A353516 * A351577 A328572 A016554

Adjacent sequences: A381029 A381030 A381031 * A381033 A381034 A381035

Keyword

nonn

Author

Antti Karttunen, Feb 13 2025

Status

approved