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A285101
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a(0) = 2, for n > 0, a(n) = a(n-1)*A242378(n,a(n-1)), where A242378(n,a(n-1)) shifts the prime factorization of a(n-1) n primes towards larger primes with A003961.
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7
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2, 6, 210, 3573570, 64845819350301990, 28695662573739152697846686144187168109530, 1038300112150956151877699324649731518883355380534272386781875587619359740733888844803014212990
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OFFSET
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0,1
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COMMENTS
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LINKS
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FORMULA
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a(0) = 2, for n > 0, a(n) = a(n-1)*A242378(n,a(n-1)).
Other identities. For all n >= 0:
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PROG
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(PARI)
A003961(n) = { my(f = factor(n)); for (i=1, #f~, f[i, 1] = nextprime(f[i, 1]+1)); factorback(f); };
(Python)
from sympy import factorint, prime, primepi
from operator import mul
from functools import reduce
def a003961(n):
f=factorint(n)
return 1 if n==1 else reduce(mul, [prime(primepi(i) + 1)**f[i] for i in f])
def a242378(k, n):
while k>0:
n=a003961(n)
k-=1
return n
l=[2]
for n in range(1, 7):
x=l[n - 1]
l.append(x*a242378(n, x))
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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STATUS
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approved
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