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A175915 Odd terms of A109510. 0
2205, 312896925, 1874196225, 3356107425, 4181881725, 4987853325, 6946213725, 8860349025, 13250605725, 17989980525, 25443641025, 32177090925, 38286871425, 55531730925, 75756402225, 113679103725, 152738872209, 170812073025, 179835853725, 186091427025 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

a(1)=2205=A109510(29), a(2)-a(8) from Max Alekseyev.

sqrt(sigma(a(n))-2*a(n)): 6, 3432, 8250, 11022, 19376.

LINKS

Table of n, a(n) for n=1..20.

PROG

(PARI) is(n)=n%2&&issquare(sigma(n)-2*n) \\ Charles R Greathouse IV, Dec 06 2011

CROSSREFS

Cf. A109510 sigma(n)-2n is a square.

Sequence in context: A125015 A252397 A252392 * A098192 A004931 A004951

Adjacent sequences:  A175912 A175913 A175914 * A175916 A175917 A175918

KEYWORD

nonn

AUTHOR

Zak Seidov, Oct 15 2010

EXTENSIONS

a(6)-a(18) from Donovan Johnson, Oct 17 2010

a(19)-a(20) from Donovan Johnson, Dec 06 2011

STATUS

approved

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Last modified July 23 12:19 EDT 2021. Contains 346259 sequences. (Running on oeis4.)