The OEIS mourns the passing of Jim Simons and is grateful to the Simons Foundation for its support of research in many branches of science, including the OEIS.
login
The OEIS is supported by the many generous donors to the OEIS Foundation.

 

Logo
Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A277200 Even terms in A260442 (in A260443). 5
2, 6, 18, 30, 90, 210, 270, 450, 630, 2310, 6750, 6930, 9450, 15750, 20250, 22050, 30030, 47250, 90090, 330750, 510510, 727650, 1212750, 1531530, 1653750, 2668050, 3543750, 4961250, 8489250, 9699690, 18191250, 24806250, 25467750, 29099070, 40020750, 53156250, 57881250, 104053950, 173423250, 173643750 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,1
COMMENTS
All odd terms larger > 1 in A260442 can be obtained from these terms by shifting their prime factorization some number of steps towards larger primes with A003961.
LINKS
PROG
(PARI)
allocatemem(2^30);
A061395(n) = if(1==n, 0, primepi(vecmax(factor(n)[, 1]))); \\ After M. F. Hasler's code for A006530.
A048675(n) = my(f = factor(n)); sum(k=1, #f~, f[k, 2]*2^primepi(f[k, 1]))/2; \\ Michel Marcus, Oct 10 2016
A003961(n) = my(f = factor(n)); for (i=1, #f~, f[i, 1] = nextprime(f[i, 1]+1)); factorback(f); \\ From Michel Marcus
A260443(n) = if(n<2, n+1, if(n%2, A260443(n\2)*A260443(n\2+1), A003961(A260443(n\2))));
isA277200(n) = (!(n%2) && (omega(n) == A061395(n)) && (A260443(A048675(n)) == n));
i=1; n=0; while(i < 100, n++; if(isA277200(n), write("b277200.txt", i, " ", n); i++));
CROSSREFS
Sequence A277324 sorted into ascending order.
Subsequence of A055932.
Cf. A002110, A277317 (subsequences, apart from their initial terms).
Also all terms of A277318 apart from initial 3 are included in this sequence.
Sequence in context: A351875 A197168 A288815 * A277324 A034881 A352813
KEYWORD
nonn
AUTHOR
Antti Karttunen, Oct 14 2016
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.

License Agreements, Terms of Use, Privacy Policy. .

Last modified May 18 03:12 EDT 2024. Contains 372617 sequences. (Running on oeis4.)