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A176258 Numbers of the form 4k+1 with greatest prime divisor of the form 4m-1. 5
9, 21, 33, 49, 57, 69, 77, 81, 93, 105, 121, 129, 133, 141, 161, 165, 177, 189, 201, 209, 213, 217, 237, 245, 249, 253, 285, 297, 301, 309, 321, 329, 341, 345, 361, 381, 385, 393, 413, 417, 437, 441, 453, 465, 469, 473, 489, 497, 501, 513, 517, 525, 529, 537, 553, 573 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

All terms of A107978 are in the sequence.

LINKS

Amiram Eldar, Table of n, a(n) for n = 1..10000

MATHEMATICA

Select[4 Range@ 150 + 1, Mod[#, 4] == 3 &[FactorInteger[#][[-1, 1]]] &] (* Michael De Vlieger, Feb 07 2016 *)

PROG

(PARI) isok(n) = (n != 1) && ((n % 4) == 1) && ((vecmax(factor(n)[, 1]) % 4) == 3); \\ Michel Marcus, Feb 07 2016

CROSSREFS

Cf. A176257, A176256, A176255, A107978, A002148, A002145, A016813, A004767.

Sequence in context: A176256 A017629 A216240 * A107978 A226355 A253052

Adjacent sequences:  A176255 A176256 A176257 * A176259 A176260 A176261

KEYWORD

nonn

AUTHOR

Vladimir Shevelev, Apr 13 2010

EXTENSIONS

Corrected and extended by Michel Marcus, Feb 07 2016

STATUS

approved

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Last modified July 12 16:03 EDT 2020. Contains 335665 sequences. (Running on oeis4.)