A342667 Largest prime in the numerator of ratio A341528(n)/A341529(n) (when presented in its lowest terms).

1, 2, 3, 13, 5, 2, 7, 2, 31, 5, 11, 13, 13, 7, 3, 11, 17, 31, 19, 13, 7, 11, 23, 2, 19, 13, 13, 13, 29, 2, 31, 13, 11, 17, 5, 31, 37, 19, 13, 5, 41, 7, 43, 11, 31, 23, 47, 11, 7, 19, 17, 13, 53, 13, 11, 7, 19, 29, 59, 13, 61, 31, 31, 1093, 13, 11, 67, 17, 23, 5, 71, 31, 73, 37, 19, 19, 7, 13, 79, 11, 71, 41, 83, 13

Offset

1,2

Comments

Equally, largest prime in the denominator of ratio A342661(A003961(n)) / A342662(A003961(n)).

Links

Table of n, a(n) for n=1..84.

Index entries for sequences computed from indices in prime factorization

Index entries for sequences related to sigma(n)

Formula

a(n) = A006530(A341526(n)).

a(n) = A006530(A342664(A003961(n))).

Prog

(PARI)
A003961(n) = { my(f = factor(n)); for (i=1, #f~, f[i, 1] = nextprime(f[i, 1]+1)); factorback(f); };
A006530(n) = if(n>1, vecmax(factor(n)[, 1]), 1);
A341526(n) = { my(s=A003961(n)); numerator((sigma(s)*n)/(sigma(n)*s)); };
A342667(n) = A006530(A341526(n));

Crossrefs

Cf. A000203, A003961, A006530, A064989, A341526, A341528, A341529, A326041, A342661, A342662, A342664, A342668.

Cf. also A341607.

Sequence in context: A069870 A067180 A067182 * A191000 A361831 A085402

Adjacent sequences: A342664 A342665 A342666 * A342668 A342669 A342670

Keyword

nonn

Author

Antti Karttunen, Mar 23 2021

Status

approved