The OEIS is supported by the many generous donors to the OEIS Foundation.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A354195 a(n) = A064989(sigma(sigma(A003961(n)))), where A003961 shifts the prime factorization one step towards larger primes, and A064989 shifts it back towards smaller primes. 4
 1, 5, 2, 5, 6, 6, 5, 12, 1, 20, 2, 10, 22, 29, 29, 85, 10, 5, 6, 30, 66, 6, 4, 58, 3, 66, 25, 25, 20, 113, 6, 25, 5, 58, 20, 5, 2, 20, 15, 226, 10, 220, 29, 10, 6, 12, 6, 170, 3, 15, 12, 110, 10, 145, 29, 40, 319, 78, 2, 145, 20, 18, 5, 541, 319, 29, 66, 50, 110, 78, 34, 12, 58, 6, 66, 30, 6, 87, 5, 510, 8, 58, 44 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS For any hypothetical odd perfect number opn that is not a multiple of 3, it holds that a(n) = A354197(n) = 2*n, where n = A064989(opn) is an odd number. LINKS Antti Karttunen, Table of n, a(n) for n = 1..20000 Antti Karttunen, Data supplement: n, a(n) computed for n = 1..100000 Index entries for sequences computed from indices in prime factorization Index entries for sequences related to sigma(n) FORMULA a(n) = A064989(A051027(A003961(n))). PROG (PARI) A003961(n) = { my(f = factor(n)); for(i=1, #f~, f[i, 1] = nextprime(f[i, 1]+1)); factorback(f); }; A064989(n) = { my(f=factor(n>>valuation(n, 2))); for(i=1, #f~, f[i, 1] = precprime(f[i, 1]-1)); factorback(f); }; A354195(n) = A064989(sigma(sigma(A003961(n)))); CROSSREFS Cf. A000203, A003961, A051027, A064989, A354196 [= A064989(a(A003961(n)))], A354346 [= 2*n - a(n)]. Cf. also A326042, A354197, A354199. Sequence in context: A116558 A196626 A082571 * A087300 A074455 A339161 Adjacent sequences: A354192 A354193 A354194 * A354196 A354197 A354198 KEYWORD nonn AUTHOR Antti Karttunen, May 23 2022 STATUS approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recents
The OEIS Community | Maintained by The OEIS Foundation Inc.

Last modified June 20 01:56 EDT 2024. Contains 373510 sequences. (Running on oeis4.)