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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

Table of n, a(n) for n=1..40.

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

Cf. A003961, A260442, A260443.

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: A324541 A197168 A288815 * A277324 A034881 A146345

Adjacent sequences:  A277197 A277198 A277199 * A277201 A277202 A277203

KEYWORD

nonn

AUTHOR

Antti Karttunen, Oct 14 2016

STATUS

approved

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Last modified July 17 16:38 EDT 2019. Contains 325107 sequences. (Running on oeis4.)