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A307527 Odd terms in A305236. 2
63, 513, 2107, 12625, 26533, 39609, 355023, 3190833, 4457713, 19854847, 38463283, 242138449, 370634743, 516465451, 574336561, 701607583, 1380336193, 2324581983, 4882890625, 6174434113, 12859758577, 14793096853, 20578440583, 43522669657, 85504120021 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

These are numbers of the form p^e*((p-1)*p^(e-1) + 1) where p is an odd prime and (p-1)*p^(e-1) + 1 is prime.

{A002322(a(n))} = {6, 18, 42, 100, 156, 162, ...} is a permutation of A114874 without the terms that are powers of 2 (but they don't have the same order: 6563187324027001 and 6575415997816513 are both terms but A002322(6563187324027001) = 81009000 while A002322(6575415997816513) = 80995248).

A305236 = {a(n)} U {2*a(n)} U {8, 12}.

LINKS

Jianing Song, Table of n, a(n) for n = 1..156 (all terms below 10^16)

EXAMPLE

See A305236 for examples.

PROG

(PARI) the_first_entries(nn) = my(u=[]); for(n=2, sqrt(nn), my(v=factor(n), d=#v[, 1], p=v[d, 1], e=v[d, 2]); if(isprime(n+1) && p!=2 && n==(p-1)*p^e, u=concat(u, [(n+1)*p^(e+1)]))); u=vecsort(select(i->(i<nn), u)); u

CROSSREFS

Cf. A305236, A114874, A002322.

Sequence in context: A331011 A283931 A038858 * A217264 A179537 A184448

Adjacent sequences:  A307524 A307525 A307526 * A307528 A307529 A307530

KEYWORD

nonn

AUTHOR

Jianing Song, Apr 12 2019

STATUS

approved

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Last modified January 22 19:16 EST 2020. Contains 331153 sequences. (Running on oeis4.)