login
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.
3
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
1,2
FORMULA
a(n) = lcm(A000203(n), A003961(n)).
a(n) = A341529(n) / A342671(n).
PROG
(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));
CROSSREFS
KEYWORD
nonn
AUTHOR
Antti Karttunen, Mar 20 2021
STATUS
approved