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A077035
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a(1)=7; a(n),a(n+1) are smallest > a(n-1) such that a(n-1)^2+a(n)^2=a(n+1)^2.
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0
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7, 24, 25, 60, 65, 72, 97, 4704, 4705, 11292, 12233, 79044, 79985, 124212, 147737, 430416, 455065, 504072, 679097, 24502296, 24511705, 34278300, 42140545, 68012700, 80009705, 192023292, 208025233, 356427144, 412692145, 990461148, 1072999577, 2403086064, 2631758105
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OFFSET
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1,1
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COMMENTS
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Note that each time two more terms are added simultaneously.
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LINKS
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EXAMPLE
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a(1)=7 therefore a(2)=24 and a(3)=25: 7^2+24^2=25^2; a(3)=25 therefore a(4)=60 and a(5)=65: 25^2+60^2=65^2.
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PROG
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(Python)
from math import isqrt
from sympy.ntheory.primetest import is_square
def aupton(terms):
alst = [7]
for n in range(2, terms+1, 2):
sq1, an = alst[-1]**2, alst[-1] + 1
while not is_square(sq1 + an**2): an += 1
alst.extend([an, isqrt(sq1 + an**2)])
return alst[:terms]
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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