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A052213 Numbers n with prime signature(n) = prime signature(n+1). 7
2, 14, 21, 33, 34, 38, 44, 57, 75, 85, 86, 93, 94, 98, 116, 118, 122, 133, 135, 141, 142, 145, 147, 158, 171, 177, 201, 202, 205, 213, 214, 217, 218, 230, 244, 253, 285, 296, 298, 301, 302, 326, 332, 334, 375, 381, 387, 393, 394, 429, 434, 445, 446, 453, 481 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

T. D. Noe, Table of n, a(n) for n = 1..10000

MathOverflow, Question on consecutive integers with similar prime factorizations

EXAMPLE

14 = 2^1*7^1 and 15 = 3^1*5^1, so both have prime signature {1,1}.

MATHEMATICA

pri[n_] := Sort[ Transpose[ FactorInteger[n]] [[2]]]; Select[ Range[ 2, 1000], pri[#] == pri[#+1] &]

PROG

(PARI) lista(nn) = for (n=1, nn-1, if (vecsort(factor(n)[, 2]) == vecsort(factor(n+1)[, 2]), print1(n, ", ")); ); \\ Michel Marcus, Jun 10 2015

CROSSREFS

Sequence in context: A138047 A005237 A140578 * A086263 A073143 A066613

Adjacent sequences:  A052210 A052211 A052212 * A052214 A052215 A052216

KEYWORD

easy,nonn

AUTHOR

Erich Friedman, Jan 29 2000

STATUS

approved

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Last modified July 1 23:38 EDT 2015. Contains 259128 sequences.