A342672 a(n) = lcm(sigma(n), A003961(n)), where A003961 is fully multiplicative with a(prime(k)) = prime(k+1), and sigma is the sum of divisors of n.

1, 3, 20, 63, 42, 60, 88, 135, 325, 126, 156, 1260, 238, 264, 840, 2511, 342, 975, 460, 126, 1760, 468, 696, 540, 1519, 714, 1000, 5544, 930, 2520, 1184, 1701, 3120, 1026, 3696, 20475, 1558, 1380, 4760, 1890, 1806, 5280, 2068, 3276, 13650, 2088, 2544, 50220, 6897, 4557, 6840, 14994, 3186, 3000, 6552, 11880, 1840, 2790

Offset: 1

Author

Antti Karttunen, Mar 20 2021

Keywords

• nonn

Links

• Antti Karttunen, Table of n, a(n) for n = 1..8192
• Index entries for sequences computed from indices in prime factorization
• Index entries for sequences related to sigma(n)

Crossrefs

Cf. A000203, A003961, A341529, A342671.

Programs

PARI

A003961(n) = { my(f = factor(n)); for (i=1, #f~, f[i, 1] = nextprime(f[i, 1]+1)); factorback(f); };
A342672(n) = lcm(sigma(n), A003961(n));

Formula

a(n) = lcm(A000203(n), A003961(n)).

a(n) = A341529(n) / A342671(n).