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A227028 Triangular numbers whose binary conversion, read in decimal, is prime. 1
3, 253, 595, 703, 2211, 2485, 4753, 13695, 22791, 23005, 35245, 52003, 54285, 62835, 82215, 88831, 119805, 173755, 219453, 238395, 252405, 271953, 275653, 306153, 325221, 350703, 406351, 470935, 482653, 521731, 607753, 611065, 634501, 661825, 675703, 726615 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

K. D. Bajpai and Charles R Greathouse IV, Table of n, a(n) for n = 1..10000 (first 116 terms from Bajpai)

EXAMPLE

The second term a(2) = T(22) = 253. Its binary conversion is 11111101, that is a prime number when read in decimal.

MAPLE

with(numtheory):with(StringTools):

#=Triangular numbers whose binary conversion is prime when read in decimal.

PRS:= proc(x, y)

local i, a, b, c, count;

count:=1;

for i from x to y do;

a:=(1/2)*(i)*((i)+1);

b:=convert(a, binary);

c:=isprime(b);

if c then lprint(count, a); count:=count+1; fi; od;

lprint("Finished "):

end:

PRS(1, 5000);

PROG

(PARI) isA036952(n)=my(v=binary(n)); isprime(sum(i=1, #v, v[i]*10^(#v-i)))

is(n)=ispolygonal(n, 3)&&isA036952(n)

select(isA036952, vector(10^3, i, i*(i+1)/2)) \\ Charles R Greathouse IV, Jun 28 2013

CROSSREFS

Intersection of A036952 and A000217.

Sequence in context: A075901 A028918 A213409 * A279653 A320023 A045824

Adjacent sequences:  A227025 A227026 A227027 * A227029 A227030 A227031

KEYWORD

nonn,base,less

AUTHOR

K. D. Bajpai, Jun 27 2013

STATUS

approved

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Last modified June 12 16:18 EDT 2021. Contains 344959 sequences. (Running on oeis4.)