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A302848
Permutation of natural numbers: a(1) = 1; for n > 1, a(n) = 1+A064989(A003961(n)-2).
3
1, 2, 3, 6, 4, 12, 5, 10, 20, 18, 8, 42, 7, 30, 15, 74, 14, 72, 11, 60, 48, 32, 9, 86, 44, 26, 75, 90, 24, 102, 16, 240, 21, 22, 19, 212, 23, 62, 80, 92, 38, 158, 13, 58, 168, 40, 27, 320, 66, 70, 59, 150, 35, 368, 84, 160, 110, 56, 54, 312, 34, 108, 111, 720, 45, 192, 39, 122, 78, 228, 68, 662, 36, 50, 33, 112, 87, 134, 17, 328, 416, 114, 47, 300, 128
OFFSET
1,2
FORMULA
a(1) = 1; for n > 1, a(n) = 1+A064989(A003961(n)-2).
a(1) = 1; for n > 1, a(n) = 1+A064216(A048673(n)-1).
PROG
(PARI)
A003961(n) = my(f = factor(n)); for (i=1, #f~, f[i, 1] = nextprime(f[i, 1]+1)); factorback(f); \\ From A003961
A064989(n) = {my(f); f = factor(n); if((n>1 && f[1, 1]==2), f[1, 2] = 0); for (i=1, #f~, f[i, 1] = precprime(f[i, 1]-1)); factorback(f)};
A302848(n) = if(1==n, n, 1+A064989(A003961(n)-2));
CROSSREFS
Cf. A302847 (inverse).
Sequence in context: A358299 A246429 A305325 * A046202 A372127 A372031
KEYWORD
nonn
AUTHOR
Antti Karttunen, Apr 26 2018
STATUS
approved