A249735 - OEIS

A249735

Odd bisection of A003961: Replace in 2n-1 each prime factor p(k) with prime p(k+1).

1, 5, 7, 11, 25, 13, 17, 35, 19, 23, 55, 29, 49, 125, 31, 37, 65, 77, 41, 85, 43, 47, 175, 53, 121, 95, 59, 91, 115, 61, 67, 275, 119, 71, 145, 73, 79, 245, 143, 83, 625, 89, 133, 155, 97, 187, 185, 161, 101, 325, 103, 107, 385, 109, 113, 205, 127, 203, 425, 209, 169, 215, 343, 131, 235, 137, 253, 875, 139, 149, 265, 221, 217, 605, 151

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OFFSET

1,2

COMMENTS

This has the same terms as A007310 (Numbers congruent to 1 or 5 mod 6), but in different order. Apart from 1, they are the numbers that occur below the first two rows of arrays like A246278 and A083221 (A083140).

LINKS

Antti Karttunen, Table of n, a(n) for n = 1..10000

FORMULA

a(n) = A003961(2n - 1).

a(n) = A007310(A249746(n)). [Permutation of A007310, Numbers congruent to 1 or 5 mod 6.]

Other identities. For all n >= 1:

A007310(n) = a(A249745(n)).

A246277(5*a(A048673(n))) = n.

A246277(5*a(n)) = A064216(n).

PROG

(Scheme) (define (A249735 n) (A003961 (+ n n -1)))

CROSSREFS